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ACOUSTIC DESIGN FOR INPATIENT
FACILITIES IN HOSPITALS
Thesis submitted in partial fulfilment of the requirements of
London South Bank University for the degree of
Doctor of Philosophy
By
Nicola Jane Shiers
Supervisor: Professor B.M. Shield, London South Bank University
Second Supervisor: Rosemary Glanville, London South Bank University
December 2011
Acoustic Design for Inpatient Facilities in Hospitals Table of Contents
__________________________________________________________________________________________________________
i
Table of Contents
LIST OF FIGURES ………………………………………………………………………………. viii
LISTOF TABLES …………………………………………………………………………………. xiii
Acknowledgements ………………………………………………………………………………. xv
Acoustic glossary and definitions ……………………………………………………………… xvi
Chapter 1 Introduction …………………………………………………………………….. 2
Chapter 2 Acoustic standards and guidance ……………………………………………. 5
2.1 Introduction …………………………………………………………………….. 5
2.2 UK design guidance ………………………………………………………….. 5
2.2.1 HTM 08-01 …….…………………………………………………...... 6
2.3 European healthcare design guidance ……………………………………… 10
2.4 World Health Organisation guidelines ………………………………………. 11
2.5 Control of infection ……………………………………………………………. 12
2.5.1 HTM 60 ……………………………………………………………….. 12
2.5.2 National Standards of Cleanliness for the NHS…………….......... 13
2.5.3 HFN 30 Infection Control in the built environment ……………….. 14
2.6 Discussion ……………………………………………………………………... 14
2.7 Conclusions ……………………………………………………………………. 15
Chapter 3 Previous research on hospital noise ………………………………………… 16
3.1 Introduction …………………………………………………………………….. 16
3.2 Noise measurement studies …………………………………………………. 16
3.2.1 Limitations of noise measurement studies ……………………....... 18
3.2.2 Understanding the overall hospital noise climate ………………... 21
3.2.3 Identifying noise sources ………………………………………….... 22
3.2.4 Discussion ………………………………………………………….... 23
3.3 Sleep studies ………………………………………………………………….. 23
3.3.1 Modification of room acoustics and its effects on sleep …………. 24
3.3.2 Discussion …………………………………………………………… 25
3.4 The effects of behaviour modification on hospital noise ………………….. 25
3.4.1 Discussion ……………………………………………………………. 26
3.5 The effects of room acoustic design modifications ………………………… 27
3.5.1 Control of infection and room acoustics ………………………….. 27
3.5.2 Physiological response to acoustic modification …………........... 28
3.5.3 Discussion ………………………………………………………….... 29
3.6 Conclusions …………………………………………………………………..... 29
Chapter 4 The effects of noise on staff and patients …………………………………. 30
Acoustic Design for Inpatient Facilities in Hospitals Table of Contents
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ii
4.1 Introduction ……………………………………………..………………………. 30
4.2 Effects of noise on staff ……………………………………………………….. 30
4.2.1 Stress levels and burnout …………………………………………… 30
4.2.2 Cognitive function / memory ………………………………………… 30
4.2.3 Effects of acoustic design on the work environment …………...... 31
4.2.4 Discussion ……………………………………………………………. 31
4.3 Effects of noise on patients ………………………………………………….. 32
4.3.1 Recovery rates ……………………………………………………… 32
4.3.2 Subjective response to noise ………………………………………. 32
4.3.3 Speech privacy ………………………………………………………. 33
4.3.4 Single bed patient rooms …………………………………………… 33
4.3.5 Discussion ……………………………………………………………. 33
4.4 Conclusions …………………………………………………………………….. 34
Chapter 5 Study design ………………………………………………………………...… 35
5.1 Introduction ……………………………………………………………………. 35
5.2 Study outline – aims and objectives ………………………………………… 35
5.2.1 Acoustic survey ……………………………………………………… 36
5.2.2 Questionnaire surveys ……………………………………………… 36
5.2.3 Comparison studies ………………………………………………… 37
5.3 Acoustic survey methodology ………………………………………………. 38
5.3.1 Equipment ……………………………………………………………. 38
5.3.2 Control of Infection ………………………………………………….. 38
5.3.3 Acoustic parameters ………………………………………………… 39
5.3.4 Presentation of sound levels ……………………………………….. 39
5.3.5 Measurement interval ……………………………………………….. 39
5.3.6 Measurement locations …………………………………………….. 39
5.3.7 Identifying sources of high level noise without an observer …….. 40
5.3.8 Reverberation times ………………………………………………….. 40
5.4 Questionnaire survey design ……………………………………………….. 40
5.4.1 Staff questionnaires …………………………………………………. 41
5.4.2 Patient questionnaires ………………………………………………. 41
5.5 Preliminary work ……………………………………………………………… 42
5.5.1 Building relationships with hospitals and Healthcare Trusts …….. 42
5.5.2 Ethics and Trust approval …………………………………………… 43
5.6 Conclusions …………………………………………………………………….. 44
Chapter 6 Pilot study ……………………………………...……………………………….. 45
6.1 Introduction ……………………………………………………………………... 45
6.2 Background …………………………………………………………………….. 45
6.3 Sky Ward ……………………………………………………………………….. 46
6.4 Building acoustic design considerations …………………………………….. 47
6.4.1 Nurse stations and common areas ………………………………… 47
6.4.2 Patient accommodation ……………………………………………… 47
Acoustic Design for Inpatient Facilities in Hospitals Table of Contents
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6.5 Ward routines ……………………………………………………………………48
6.5.1 Staffing and patient levels …………………………………………… 48
6.5.2 Staff shift patterns and ward rounds ……………………………….. 49
6.5.3 Cleaning ……………………………………………………………….. 49
6.5.4 Meal times …………………………………………………………….. 49
6.5.5 Medical equipment with alarms …………………………………….. 49
6.5.6 Access to patient accommodation …………………………………. 49
6.6 Measurement locations ……………………………………………………….. 50
6.6.1 Nurse stations ………………………………………………………… 50
6.6.2 Four bed bays ………………………………………………………… 53
6.6.3 Single patient rooms …………………………………………………. 55
6.7 Equipment and microphone positioning ……………………………………... 56
6.7.1 Nurse stations ………………………………………………………… 57
6.7.2 Four bed bays ………………………………………………………… 57
6.7.3 Single patient rooms …………………………………………………. 58
6.8 Other considerations ……………………………………………………………58
6.8.1 Identifying the optimal ‘level above’ setting for trigger files ……… 58
6.8.2 Publicising the study …………………………………………………. 59
6.8.3 Reverberation times ………………………………………………….. 59
6.9 Questionnaire survey considerations ………………………………………… 60
6.10 Overall acoustic survey results ……………………………………………….. 60
6.11 Nurse stations ………………………………………………………………….. 62
6.11.1 Sources of high level noise …………………………………………. 63
6.12 Four bed bays ………………………………………………………………….. 66
6.12.1 Sources of high level noise …………………………………………. 67
6.13 Single patient rooms …………………………………………………………… 69
6.13.1 Sources of high level noise …………………………………………. 70
6.14 Establishing a representative measurement interval ……………………… 71
6.15 Other measured acoustic parameters ………………………………………. 73
6.15.1 Reverberation times …………………………………………………. 73
6.15.2 Ambient noise levels ………………………………………………… 74
6.16 Results of the staff questionnaire surveys ……………….…………………. 75
6.16.1 Staff profile ……………………………………………………………. 75
6.16.2 Noise annoyance and interference ………………………………… 75
6.16.3 Important sounds …………………………………………………….. 78
6.17 Patient questionnaires …………………………………………………………. 79
6.17.1 Parent / patient profile ……………………………………………….. 79
6.17.2 Noise annoyance …………………………………………………….. 80
6.17.3 Positive sounds ………………………………………………………. 82
6.17.4 Privacy and ease of hearing ………………………………………… 83
6.17.5 Patient’s questionnaire comments …………………………………. 83
6.18 Summary of results ………………………………………………………….. 83
6.19 Follow up discussions ………………………………………………………… 84
6.20 Conclusions ……………………………………………………………………. 87
Acoustic Design for Inpatient Facilities in Hospitals Table of Contents
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Chapter 7 Bedford Hospital …………………………………………………….…………. 91
7.1 Introduction ……………………………………………………………………... 91
7.2 Background …………………………………………………………………….. 91
7.3 Building acoustic design considerations ……………………………………. 92
7.4 Hospital policies and equipment common to both wards ………………… 92
7.4.1 Meal times …………………………………………………………… 92
7.4.2 Ward design …………………………………………………………. 93
7.4.3 Occupancy levels …………………………………………………… 94
7.4.4 Shift patterns ………………………………………………………… 94
7.4.5 Visiting hours ………………………………………………………… 94
7.4.6 Ward access …………………………………………………………. 94
7.4.7 Access to patient accommodation ………………………………… 94
7.4.8 Cleaning staff ………………………………………………………… 94
7.4.9 Mobile phone policy …………………………………………………. 94
7.4.10 Entertainment systems ……………………………………………… 95
7.4.11 Rubbish bins ………………………………………………………….. 95
7.4.12 Staff call ……………………………………………………………….. 95
7.4.13 Medical equipment alarms ………………………………………….. 95
7.4.14 Trolleys ………………………………………………………………... 95
7.4.15 Internal telephones …………………………………………………… 95
7.4.16 Hand gels ……………………………………………………………… 95
7.5 Medical ward ……………………………………………………………………. 96
7.5.1 Ward specific information ……………………………………………. 98
7.6 Medical ward overall noise survey results ……………………………………100
7.6.1 Nurse station and ward entrance …………………………………… 101
7.6.2 Multi-bed bays ………………………………………………………… 103
7.6.3 Single patient rooms …………………………………………………. 105
7.6.4 Further analysis of high level noise sources ………………………. 106
7.7 Surgical ward …………………………………………………………………… 109
7.7.1 Ward specific information ……………………………………………. 109
7.8 Surgical ward overall noise survey results ………………………………….. 112
7.8.1 Nurse station ……………………..…………………………………… 113
7.8.2 Multi-bed bays ………………………………………………………… 115
7.8.3 Single patient rooms …………………………………………………. 116
7.8.4 Further analysis of high level noise sources ………………………. 118
7.9 Results of the staff questionnaire surveys ….………………………........... 120
7.9.1 Staff profile ……………………………………………………………. 120
7.9.2 Noise annoyance …………………………………………………….. 121
7.9.3 Interference with work ………………………………………………. 124
7.9.4 Important sounds …………………………………………………….. 125
7.10 Results of the patient questionnaire surveys ……………………………….. 126
7.10.1 Patient profiles.………………………………………………………... 126
7.10.2 Noise annoyance and disturbance …………………………………. 127
7.10.3 Positive sounds ……..………………………………………………... 131
7.10.4 Ease of hearing and privacy ………………………………………... 132
7.11 Questionnaire comments …………………………………………………….. 132
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7.12 Summary ………………………………………………………………………. 132
7.13 Conclusions ……………………………………………………………………. 133
Chapter 8 Ceiling intervention study, Bedford Hospital ………………………………. 135
8.1 Introduction …………………………………………………………………….. 135
8.2 Bay information ………………………………………………………………… 136
8.3 Effect of ceiling tile change on noise levels …………………………………. 137
8.4 Effect of ceiling tile change on reverberation time ………………………….. 140
8.4.1 Unoccupied reverberation times ……………………………………. 140
8.4.2 Occupied reverberation times ………………………………………. 141
8.5 Comparison of unoccupied and occupied RTs …………………………….. 142
8.6 Conclusions …………………………………………………………………….. 143
Chapter 9 Addenbrooke’s Hospital .......……………………………………………......... 144
9.1 Introduction …………………………………………………………………….. 144
9.2 Background …………………………………………………………………….. 144
9.3 Ward D8 (surgical) …………………………………………………………….. 145
9.3.1 Building design ………………………………………………………. 145
9.3.2 Ward layout …………………………………………………………… 146
9.3.3 Ward specific information …………………………………………… 146
9.3.4 Managing the study ………………………………………………….. 148
9.4 Overall noise survey results Ward D8 ……………………………………… 151
9.4.1 Nurse station …………………………………………………………. 152
9.4.2 Multi-bed bays ……………………………………………………….. 154
9.4.3 Further analysis of high level noise sources ……………………… 155
9.4.4 Representative measurement interval …………………………….. 158
9.5 Ward N3 (medical) ……………………………………………………………. 160
9.5.1 Building design ………………………………………………………. 160
9.5.2 Ward layout …………………………………………………………… 160
9.5.3 Ward specific information …………………………………………… 161
9.5.4 Managing the study ………………………………………………….. 163
9.6 Overall noise survey results Ward N3 ……………………………………….. 166
9.6.1 Nurse station …………………………………………………………. 167
9.6.2 Multi-bed bays ……………………………………………………….. 170
9.6.3 Single patient rooms ………………………………………………… 171
9.6.4 Further analysis of high level noise sources ……………………… 172
9.7 Ward M4 (surgical) …………………………………………………………….. 174
9.7.1 Building construction …………..…………………………………….. 174
9.7.2 Ward layout …………………………………………………………… 174
9.7.3 Ward specific information …………………………………………… 175
9.7.4 Managing the study ………………………………………………….. 177
9.8 Overall noise survey results Ward M4 ……………………………………….. 181
9.8.1 Nurse station …………………………………………………………. 182
9.8.2 Multi-bed bays ……………………………………………………….. 184
9.8.3 Single patient rooms ………………………………………………… 185
Acoustic Design for Inpatient Facilities in Hospitals Table of Contents
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9.8.4 Further analysis of high level noise sources ……………………… 186
9.9 Results of the staff questionnaire surveys ….………………………........... 188
9.9.1 Staff profile ……………………………………………………………. 188
9.9.2 Noise annoyance …………………………………………………….. 189
9.9.3 Interference with work ……………………………………………….. 190
9.9.4 Important sounds …………………………………………………….. 192
9.10 Results of the patient questionnaire surveys ……………………………….. 193
9.10.1 Patient profiles.……………………………………………………….. 193
9.10.2 Noise annoyance and disturbance ………………………………… 194
9.10.3 Positive sounds ……..……………………………………………….. 198
9.10.4 Ease of hearing and privacy ………………………………………… 199
9.11 Questionnaire comments …………………………………………………….. 199
9.12 Summary ………………………………………………………………………. 199
9.13 Conclusions ……………………………………………………………………. 201
Chapter 10 Blind estimation of reverberation time ………………………………………. 202
10.1 Introduction …………………………………………………………………….. 202
10.2 Initial validation ………………………………………………………………… 202
10.3 Validation using real and simulated measurements ………………………. 203
10.3.1 Validation 1 …………………………………………………………… 204
10.3.2 Validation 2 …………………………………………………………… 205
10.3.3 Validation study conclusions ………………………………………… 207
10.4 Estimation of RT in occupied hospital wards ……………………………….. 208
10.4.1 Methodology ………………………………………………………….. 208
10.4.2 MLE-RT20 estimates from day time data …………………………... 209
10.5 Comparison of day and night time MLE-RT20 estimates …………………… 212
10.6 Summary ………………………………………………………………………. 214
10.7 Conclusions …………………………………………………………………… 215
Chapter 11 Analysis of objective and subjective data …………………………………… 216
11.1 Introduction ……………………………………………………………………... 216
11.2 Factors affecting noise levels ……………………………………………… 216
11.2.1 Effect of bay size ……………………………………………………… 216
11.2.2 Surgical and medical wards ………………………………………… 219
11.2.3 Impact of high level noise events on overall noise levels …………220
11.2.4 Noise levels and reverberation times ………………………………. 221
11.3 Factors affecting patient perceptions of noise ……………………………. 222
11.3.1 Overall ………………………………………………………………… 222
11.3.2 Patient gender ……………………………………………………….. 224
11.3.3 Age ……………………………………………………………………. 225
11.3.4 Hearing impairment …………………………………………………. 226
11.3.5 Length of stay ……………………………………………………….. 227
11.3.6 Bed position ………………………………………………………….. 229
11.3.7 Speech intelligibility and privacy …………………………………… 230
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11.4 Factors affecting staff perceptions of noise ………………………………… 231
11.4.1 Overall ………………………………………………………………… 231
11.4.2 Staff gender …………………………………………………………… 231
11.4.3 Age …………………………………………………………………….. 232
11.4.4 Time worked on the ward …………………………………………… 233
11.4.5 Time worked at the hospital ………………………………………… 233
11.4.6 Relationship between noise annoyance and noise interference … 234
11.5 Discussion ………………………………………………………………………. 234
11.6 Conclusions …………………………………………………………………… 236
Chapter 12 Noise control in inpatient care …..…………………………………………… 237
12.1 Introduction …………………………………………………………………….. 237
12.2 Optimising the acoustic design of the ward ………..……………………….. 237
12.2.1 Design for infection control ………………………………………… 237
12.2.2 The effects of adding acoustic absorbency………..……………… 238
12.2.3 Ward design …………………………………………………………. 238
12.2.4 Building construction ……………………………………………….. 239
12.2.5 Building age and overall noise levels ……………………………... 240
12.3 Ward equipment ….……….…………………………………………………. 242
12.3.1 Nurse call systems …………………………………………………… 242
12.3.2 Internal telephones …………………………………………………… 242
12.3.3 Medical equipment alarms ………………………………………….. 243
12.3.4 Doorbell ……………………………………………………………….. 244
12.3.5 Rubbish bins ………………………………………………………….. 244
12.3.6 Ward furniture ………………………………………………………… 244
12.3.7 Wheeled equipment ………………………………………………….. 244
12.3.8 Ring binders …………………………………………………………... 245
12.3.9 Doors …………………………………………………………………... 245
12.4 Human behaviour ……………………………………………………………… 245
12.5 WHO guidelines ………………………………………………………………. 247
12.6 Acoustic parameters …………………………………………………………. 247
12.7 Conclusions …………………………………………………………………… 248
Chapter 13 Conclusions ……………………………………………………………………. 249
13.1 Introduction …………………………………………………………………….. 249
13.2 Overall conclusions ….………………………………………………………. 249
13.2.1 Building design ……………………………………………………….. 249
13.2.2 Patient accommodation ……………………………………………… 250
13.2.3 Staff and patient perceptions ……………………………………….. 250
13.2.4 Ward equipment ……………………………………………………… 250
13.2.5 Human behaviour …………………………………………………….. 251
13.2.6 Guidelines …………………………………………………………….. 251
13.3 Recommendations ………………..………………………………………….. 251
13.4 Further work …………………………………………………………………… 252
References ……………………….……………………………………………………………….. 253
Acoustic Design for Inpatient Facilities in Hospitals List of Figures
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LIST OF FIGURES
Figure 2.1 Recommended RTs for different room functions and volumes, HTM 2045 (NHS Estates, 1996) 9
Figure 3.1 LAeq values measured in hospitals during day time hours as a function of
the year of study publication. (Busch-Vishinac et al, 2005) 17
Figure 3.2 LAeq values measured in hospitals during night time hours as a function of
the year of study publication. (Busch-Vishinac et al, 2005) 17
Figure 5.1 Sound level meter, environmental case and associated equipment 38
Figure 6.1 The Octav Botnar Wing 46
Figure 6.2 Main entrance to the Octav Botnar Wing 46
Figure 6.3 Sky Ward Reception 47
Figure 6.4 Typical four bed bay 47
Figure 6.5 Ultima ceiling tile sound absorption coefficients (α) over a range of frequencies 48
Figure 6.6 Layout of Sky Ward with microphone positions 51
Figure 6.7 Nurse Station 1 50
Figure 6.8 Internal corridor 50
Figure 6.9 Internal telephone & security monitor 52
Figure 6.10 Wall mounted speaker grill 52
Figure 6.11 Nurse station 2 53
Figure 6.12 Nurse station 2 desk 53
Figure 6.13 4-bed bay B 54
Figure 6.14 Hand washing sink, door to shower room and lockers 54
Figure 6.15 Patient bed and fold down chair 54
Figure 6.16 Ward entrance with rubbish bins 54
Figure 6.17 Patient bed showing bed head services 55
Figure 6.18 Locked door onto balcony 55
Figure 6.19 Door to ensuite, pull down bed, sink and rubbish bins 55
Figure 6.20 Patient bed and opening windows 56
Figure 6.21 Rubbish bins and hand washing sink 56
Figure 6.22 Pull down bed 56
Figure 6.23 Flat screen television 56
Figure 6.24 Microphone position at nurse station 1 57
Figure 6.25 Microphone position at nurse station 2 57
Figure 6.26 4-bed bay B with microphone placed on top of lockers 58
Figure 6.27 Single patient room 1 with microphone position shown 58
Figure 6.28 Single patient room 2 with microphone position shown 58
Figure 6.29 Average day and night LAeq levels measured at each location 62
Figure 6.30 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations 63
Figure 6.31 Nurse call console 64
Figure 6.32 The number and levels (LAmax) of occurrences of the nurse call system
at nurse station 1, measured at 3 m over 5 days 64
Figure 6.33 The number and levels (LAmax) of occurrences of the ward doorbell at
nurse station 2, measured at 3 m over 19 hours 65
Figure 6.34 Average LAmax of the nurse call system, internal telephone and ward doorbell 66
Figure 6.35 Average LAeq,1hr and LA90,1hr levels over 24 hours for 4-bed bays A and B 67
Figure 6.36 Percentages of high level noise events by type measured in 4-bed bays A and B 68
Acoustic Design for Inpatient Facilities in Hospitals List of Figures
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Figure 6.37 Average LAeq,1hr and LA90,1hr levels over 24 hours for single patient rooms
A and B 69
Figure 6.38 Percentages of high level noise events by type for single patient rooms
A & B 70
Figure 6.39 LAeq,1hr levels measured over five consecutive days at nurse station 1 72
Figure 6.40 Average LAeq,1hr levels over 24 hours for week 1 and week 2 at nurse station 1 72
Figure 6.41 Distribution of the extent of staff annoyance 76
Figure 6.42 Percentage of staff rating an annoyance noise event with a 2, 3 or 4 76
Figure 6.43 Distribution of the extent of noise interference with work 77
Figure 6.44 Percentage of staff rating an interference noise event with a 2, 3 or 4 78
Figure 6.45 Mean importance rating of certain noise events 79
Figure 6.46 Parents by age bracket 79
Figure 6.47 Patients by age bracket 79
Figure 6.48 Distribution of the extent of parent / patient annoyance during the day time 80
Figure 6.49 Percentage of parents / patients rating an annoyance noise event with a 2, 3 or 4 81
Figure 6.50 Distribution of the extent of parent / patient disturbance during the night time 81
Figure 6.51 Percentage of parents / patients rating a disturbance noise event with a 2, 3 or 4 82
Figure 7.1 Original building, Bedford Hospital (1803) 91
Figure 7.2 Five storey ward block 92
Figure 7.3 Main hospital entrance 92
Figure 7.4 Medical ward kitchen 93
Figure 7.5 Hospicom entertainment console 96
Figure 7.6 Automatic hand gel dispenser 96
Figure 7.7 Single patient room 96
Figure 7.8 Microphone suspended from ceiling 97
Figure 7.9 Microphone on tripod 97
Figure 7.10 Detailed plan of the medical ward showing microphone positions 99
Figure 7.11 Average day and night LAeq levels measured at each location 101
Figure 7.12 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station
and ward entrance 102
Figure 7.13 LAmax,2s and LAeq,2s fluctuating over a ten minute interval at the nurse station 102
Figure 7.14 Average LAeq,1hr levels over 24 hours for the multi-bed bays 104
Figure 7.15 Average LA90,1hr levels over 24 hours for the multi-bed bays 104
Figure 7.16 Average LAeq,1hr levels over 24 hours for the single rooms 105
Figure 7.17 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a three
hour period in single room A 106
Figure 7.18 Average number of high level noise events recorded at each location per day 106
Figure 7.19 Average number of high level noise events recorded at each location per night 108
Figure 7.20 Detailed plan of the surgical ward showing microphone positions 111
Figure 7.21 Average day and night LAeq levels measured at each location 113
Figure 7.22 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station 113
Figure 7.23 LAmax,2s (green trace) and LAeq,2s (red trace) measured over a thirty
minute interval during the night (2.40am onwards) at the nurse station 114
Figure 7.24 LAmax,2s and LAeq,2s fluctuating over a 11 minute interval at the nurse station 115
Figure 7.25 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr
level for all bays over 24 hours 116
Figure 7.26 Average LAeq and LA90 levels for single rooms A and B and multi-bed bays 117
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Figure 7.27 LAmax,2s (green trace) and LAeq,2s (red trace) showing the noise levels
due to a medical equipment alarm over a period of 13 minutes 118
Figure 7.28 Average number of high level noise events captured at each location per day 119
Figure 7.29 Average number of high level noise events captured at each location per night 120
Figure 7.30 Age of respondents by band 121
Figure 7.31 Time worked on the ward 121
Figure 7.32 Time worked at the hospital 121
Figure 7.33 Staff perception of noise in terms of annoyance 122
Figure 7.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4 123
Figure 7.35 Staff perception of the extent to which noise interferes with work 124
Figure 7.36 The percentages of staff rating an interference noise event with a 2, 3 or 4 124
Figure 7.37 Mean importance rating of certain noise events 125
Figure 7.38 Gender split by ward type 126
Figure 7.39 Patients age by band 126
Figure 7.40 Length of patient stay when completing the questionnaire 127
Figure 7.41 Patient perception of the day time ward noise environment 128
Figure 7.42 The percentage of patients rating an annoyance noise event with a 2, 3 or 4 129
Figure 7.43 Patient perception of the night time ward noise environment 130
Figure 7.44 The percentage of patients rating a disturbance noise event with a 2, 3 or 4 131
Figure 8.1 Photographs of the bay during refurbishment 135
Figure 8.2 Absorption coefficients of Armstrong Bioguard Plain ceiling tiles Source: Manufacturer’s product specification sheet 136
Figure 8.3 Absorption coefficients of Armstrong Bioguard Acoustic ceiling tiles Source: Manufacturer’s product specification sheet 136
Figure 8.4 Average LAeq,1hr levels over 24 hours pre and post ceiling change 138
Figure 8.5 Average number of trigger files recorded over 24 hours by event type 139
Figure 8.6 The frequency content of noise of metal cutlery 139
Figure 8.7 Source (S) and receiver (R) positions used to measure reverberation
time in the unoccupied bay before and after the ceiling change 140
Figure 8.8 Average unoccupied RT20 measurements with 95% confidence limits
(Impulse Response Method) 141
Figure 8.9 Occupied MLE-RT20 estimates pre and post the ceiling replacement 142
Figure 9.1 Original building, Addenbrooke’s Hospital 144
Figure 9.2 Detailed plan of ward D8 showing microphone positions 150
Figure 9.3 Average day and night LAeq levels measured at each location 152
Figure 9.4 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station 153
Figure 9.5 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a ten
minute interval at the nurse station during the night 153
Figure 9.6 Average LAeq,1hr levels over 24 hours for the multi-bed bays 155
Figure 9.7 Average number of high level noise events recorded at each location per day 156
Figure 9.8 Average number of high level noise events recorded at each location per night 157
Figure 9.9 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 19 minute
interval at in the elderly trauma unit 158
Figure 9.10 Average LAeq,1hr levels over 24 hours for two non-consecutive weeks in
the 12-bed bay 159
Figure 9.11 Detailed plan of the ward N3 showing microphone positions 165
Figure 9.12 Average day and night LAeq levels measured at each location 167
Figure 9.13 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station 168
Acoustic Design for Inpatient Facilities in Hospitals List of Figures
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Figure 9.14 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 13 minute
interval at the nurse station during the afternoon 168
Figure 9.15 Frequency content of door bang at the nurse station 169
Figure 9.16 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level
for all bays over 24 hours 170
Figure 9.17 Average LAeq,1hr levels over 24 hours for the single rooms 171
Figure 9.18 Average number of high level noise events recorded at each location per day 172
Figure 9.19 Average number of high level noise events recorded at each location per night 173
Figure 9.20 Percentage break down of high level noise events by type in 4-bed bay B 173
Figure 9.21 Plan of Ward M4 detailing shared areas and microphone positions 179
Figure 9.22 Detailed plan of Ward M4 showing study locations and microphone positions 180
Figure 9.23 Average day and night LAeq levels measured at each location 182
Figure 9.24 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations 183
Figure 9.25 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 15 minute
interval at the nurse station at 05.30 183
Figure 9.26 Average LAeq,1hr and LA90,1hr level for each multi-bed bay over 24 hours 184
Figure 9.27 Average LAeq,1hr and LA90,1hr levels over 24 hours for the single rooms 185
Figure 9.28 Average number of high level noise events recorded at each location per day 187
Figure 9.29 Average number of high level noise events recorded at each location per night 187
Figure 9.30 Age of respondents by band 188
Figure 9.31 Time worked on the ward 189
Figure 9.32 Time worked at the hospital 189
Figure 9.33 Staff perception of noise in terms of annoyance 189
Figure 9.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4 190
Figure 9.35 Staff perception of the extent to which noise interferes with work 191
Figure 9.36 The percentages of staff rating an interference noise event with a 2, 3 or 4 191
Figure 9.37 Mean importance rating of certain noise events 192
Figure 9.38 Gender split by ward type 193
Figure 9.39 Patients age by band 193
Figure 9.40 Length of patient stay when completing the questionnaire 194
Figure 9.41 Patient perception of the day time ward noise environment 195
Figure 9.42 The percentages of patients on Ward D8 rating an annoyance noise
event with a 2, 3 or 4 196
Figure 9.43 Patient perception of the night time ward noise environment 197
Figure 9.44 The percentages of patients rating a disturbance noise event with a 2, 3 or 4 198
Figure 10.1 Clinical skills laboratory used for validation 1 204
Figure 10.2 Average RT20 measurements with 95% confidence limits
(Impulse Response Method) 204
Figure 10.3 Average RT20 measurements with 95% confidence limits
(Impulse Response Method) 207
Figure 10.4 Accuracy of RT20 estimations in relation to actual measured values
Figure 10.5 MLE-RT20 estimates for five multi-bed bays in Ward D8, Addenbrooke’s
Hospital (day time data) with 95% confidence limits 210
Figure 10.6 MLE-RT20 estimates for six locations in Ward N3, Addenbrookes
Hospital (day time data) with 95% confidence limits 210
Figure 10.7 MLE-RT20 estimates for seven locations in the surgical ward,
Bedford Hospital (day time data) with 95% confidence limits 211
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Figure 10.8 Comparison of day and night time estimates, 7-bed bay, Ward D8,
Addenbrooke’s Hospital 212
Figure 10.9 Comparison of day and night time estimates, 12-bed bay, Ward D8,
Addenbrooke’s Hospital 213
Figure 10.10 Comparison of day and night time estimates, 4-bed bay,
medical ward, Bedford Hospital 213
Figure 11.1 Average day time levels by bay size for all main study wards 218
Figure 11.2 Average night time levels by bay size for all main study wards 218
Figure 11.3 Average day time noise levels and average number of day time high level
noise events for each bay 220
Figure 11.4 Average night time noise levels and average number of night time high
level noise events for each bay 221
Figure 11.5 Average day time noise levels and estimated reverberation times in each bay 222
Figure 11.6 Overall patient perception of the noise climate 223
Figure 11.7 Overall percentages of patient annoyed / disturbed by noise 223
Figure 11.8 Mean patient perception rating of noise by gender 224
Figure 11.9 Percentages of patients annoyed / disturbed by noise by gender 224
Figure 11.10 Mean rating of patient perceptions of day and night noise and age 225
Figure 11.11 Percentages of patients annoyed / disturbed and age 226
Figure 11.12 Percentage of hearing impaired by age group 226
Figure 11.13 Percentage of patients annoyed / disturbed with hearing impairment 227
Figure 11.14 Mean rating of patient perceptions of day and night noise and length of stay 228
Figure 11.15 Percentages of patients annoyed / disturbed and length of stay 228
Figure 11.16 Percentages of patients annoyed / disturbed and bed position 229
Figure 11.17 Patient privacy and bay size 230
Figure 11.18 Staff levels of annoyance and interference 231
Figure 11.19 Level of noise annoyance / interference by staff gender 232
Figure 11.20 Level of noise annoyance / interference by staff age 232
Figure 11.21 Level of noise annoyance / interference by time worked on the ward 232
Figure 11.22 Level of noise annoyance / interference by time worked at the hospital 234
Figure 12.1 Average day time levels by building age for all patient accommodation 241
Figure 12.2 Average night time levels by building age for all patient accommodation 241
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LIST OF TABLES
Table 2.1 Example of criteria for intrusive noise from external sources, HTM 08-01
(The Stationary Office, 2008) 7
Table 2.2 Example of criteria for internal noise from mechanical and electrical
services, HTM 08-01 (The Stationary Office, 2008) 7
Table 2.3 Example of sound insulation parameters of rooms, HTM 08-01
(The Stationary Office, 2008) 8
Table 2.4 Example of sound insulation ratings (dB, DnT,w) to be achieved
on site, HTM 08-01 (The Stationary Office, 2008) 8
Table 2.5 Extract from Chapter 8 ‘Checklists’, HTM 08-01
(The Stationary Office, 2008) 10
Table 2.6 Standards and guidelines for healthcare design in Europe
(from Bergman and Janssen, 2008) 11
Table 2.7 Acoustic parameters (from Bergman and Janssen, 2008) 11
Table 2.8 World Health Organisation guidelines for hospital wards and treatment rooms 12
Table 2.9 Recommended ceiling characteristics for hospital room types, HTM 60
(NHS Estates, 2005) 13
Table 3.1 Measurement data from studies cited in Section 3.2 14
Table 6.1 Measurement location and time interval 60
Table 6.2 Average LAeq measured for 24 hour, day and night time periods at
each location 61
Table 6.3 Average and maximum noise levels of identified events in single room A 7 1
Table 6.4 Reverberation times measured in different ward accommodation 74
Table 6.5 Ambient noise levels measured in unoccupied patient accommodation 74
Table 7.1 Medical ward - measurement locations, time periods and patient gender 100
Table 7.2 Average LAeq measured for 24 hour, day and night time periods at
each location 100
Table 7.3 Examples of noise events at the nurse station 103
Table 7.4 Examples of noise sources and levels on the medical ward 108
Table 7.5 Measurement location, time periods and patient gender type 112
Table 7.6 Average LAeq for 24 hour, day and night time periods at each location 112
Table 8.1 Average LAeq measured during the day and night time pre and post
the ceiling change 138
Table 8.2 Reverberation times for both the unoccupied and occupied bay
pre ceiling change 1 43
Table 8.3 Reverberation times estimates for both the unoccupied and occupied
bay post ceiling change 143
Table 9.1 Ward D8 - measurement locations, time periods and patient gender 151
Table 9.2 Average LAeq measured for 24 hour, day and night time periods at
each location 151
Table 9.3 Examples of noise events at the nurse station 154
Table 9.4 Examples of noise events in the multi-bed bays 158
Table 9.5 Measurement location, time interval and patient type 166
Table 9.6 Average LAeq measured for 24 hour, day and night time periods
at each location 166
Table 9.7 Examples of noise events at the nurse station 169
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Table 9.8 Measurement location, time interval and patient gender 181
Table 9.9 Average LAeq measured for 24 hour, day and night time periods
at each location 181
Table 10.1 Comparisons between measured and MLE-RT20 values 205
Table 10.2 Numbers of triggers recorded during the simulations 206
Table 10.3 SLM 1 with curtains open 207
Table 10.4 SLM 1 with curtains drawn 207
Table 10.5 SLM 2 with curtains open 207
Table 10.6 SLM 2 with curtains drawn 207
Table 10.7 Locations with data available for MLE-RT20 estimation 208
Table 10.8 Day time data shown in 4 hour windows; overall mean estimate
with 95% confidence intervals 209
Table 11.1 Summary of the objective and subjective data collected during the study 217
Table 12.1 World Health Organisation guidelines for hospital wards and treatment rooms 248
Acoustic Design for Inpatient Facilities in Hospitals Acknowledgements
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Acknowledgements
This piece of work has been funded as a ‘Case Award’ by the Engineering and Physical
Sciences Research Council (EPSRC) and by Arup Global Healthcare.
Firstly, I would like to thank the members of the Redevelopment Team at Great Ormond
Street Children’s Hospital, and those members of the Estates Teams at Bedford Hospital and
Addenbrooke’s Hospital who facilitated this research. Without their time and support, this
research would not have been possible. I would also like to thank the study ward managers
for their cooperation, and all the ward staff and patients who have taken time to complete the
study questionnaires.
This work would also have not been possible without the unending support, patience and
kindness of my supervisor Professor Bridget Shield. I would like to thank you for having faith
in me and allowing me finally to fulfil my true potential.
I would also like to express my gratitude to my supervisor Rosemary Glanville for sharing her
extensive knowledge and experience of healthcare buildings, and for providing me with
invaluable guidance and support.
I would like to extend my thanks to Russell Richardson at RBA Acoustics who gave me the
initial opportunity to gain some valuable experience in the field of acoustics, and to Peter
Attwood of Acoustic Associates (Sussex), without whom I would never have embarked on this
journey.
Finally, a thank you to all my friends and family for believing in me and for always ‘being
there’.
Acoustic Design for Inpatient Facilities in Hospitals Glossary and definitions
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xvi
Acoustic glossary and definitions
Sound and noise
‘Sound’ refers to the harmonic pressure variations that we hear in air and is an important part of our everyday world. Too much sound can be annoying, even dangerous. ‘Noise’ usually refers to unwanted sound. General environmental and building noise consists of sound that is composed of many different frequencies.
The decibel and sound pressure
The decibel (dB) is the main measurement unit in acoustics. It can be the measure of the magnitude of sound, changes in sound level and a measure of sound insulation. The decibel is not an absolute unit, but the ratio of two levels expressed in logarithmic form.
• A 1 dB increase in level is un-noticeable in everyday life.
• A 3 dB increase would be barely perceptible (even though it is actually a doubling of sound energy).
• A 10 dB change in level is perceived as the doubling in loudness.
The pressure fluctuations caused by sound waves in air are called sound pressure. The lowest sound pressure level which can be heard is 0 dB, known as the threshold of hearing. The highest level which can be tolerated is called the pain threshold and is around 120 dB.
The response of the human ear and ‘A-Weighting’
The response of the human ear is dependent upon the frequency characteristics of the sound. The ear is not equally sensitive to sound at all frequencies, being less sensitive at low and very high frequencies, with peak response around 2500 to 3000 Hz
The vast majority of noise measurements made are in A-weighted decibels (dBA). The A-weighting is an electronic frequency weighting network which attempts to build the human response to different frequencies into the reading indicated by a sound level meter, so that it will relate to the loudness of the noise. The measured readings are denoted with either an ‘A’ as in 90 dBA or a subscript in the case of LAeq, LA90, and LAmax. The subscript ‘Z’ denotes that the measured sound level is unweighted.
A- Weighted Equivalent Sound Pressure Level (LAeq)
Most measured noise is not steady, but fluctuates significantly in level over a short period of time. It is not easy to find a measure which accurately quantifies what is heard with a single number. The LAeq is the A-weighted equivalent continuous sound pressure level. It is an average of the total amount of sound energy measured over a specified time period (commonly a 1 hour period).
If noise is measured for discrete periods of time, the overall LAeq,T can be calculated using the following equation:
LAeq,T = 10log[(t1.10L1/10
+ t2.10L2/10
+ t3.10L3/10
+ ……. TN.10LN/10
)/T]
Where t1 is the time at noise level L1 dBA
t2 is the time at noise level L2 dBA
t3 is the time at noise level L3 dBA, etc.
….and T is the time over which the value is required.
LAmax, LAmin and Statistical Parameters
The LAmax is the A-weighted maximum sound pressure level during a measurement period.
The LAmin is the A-weighted minimum sound pressure level during a measurement period.
Statistical parameters (sometimes called noise percentile levels) are the sound pressure levels exceeded for a certain percentage of the measurement period.
LA10 and LA90 are the most commonly used, where LA10 is the level exceeded for 10% of the time and LA90 is the level exceeded for 90% of the time.
LA90 is used to represent background noise levels.
Fast and Slow Time Weightings
Time weightings determine how quickly a sound level meter (SLM) responds to changes in the sound pressure level. Most measurements are now made with a fast weighting selected, unless otherwise specified by the relevant standard.
When sampling is set to ‘fast’ the SLM is sampling over a number of 0.125 s periods and all parameters are calculated from these measurements.
Acoustic Design for Inpatient Facilities in Hospitals Glossary and definitions
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xvii
When sampling is set to ‘slow’ the SLM is sampling over a number of 1 s periods and all parameters are calculated from these measurements.
As the SLM is responding more slowly when set to ‘slow’, impulsive measurements such as LAmax would give lower sound pressure level readings (as a rule of thumb 5dB less could be expected) and LAmin values would be higher than expected. The difference between LAeq measurements would not be so significant (perhaps 1dB depending on the specification of the SLM).
Frequency (Hz)
Frequency is defined as the number of oscillations per second and is measured in Hertz (Hz).
A healthy young person can hear frequencies from 20 Hz to 20,000 Hz (the lower the value the lower the pitch).
Loudness
Loudness is a measure of the subjective impression of sound
Reverberation Time (RT)
The reverberation time is defined as the time it takes for sound to decrease by 60 dB. Long reverberation times usually exist in spaces with hard surfaces and minimal sound absorption (like curtains, carpets and soft furnishings). Sounds within reverberant rooms may seem hard-edged and even echo-y. With high levels of background noise present, the nature of a reverberant room is such that speech intelligibility may be affected, causing voices to be raised.
To determine the length of the reverberation time, different parts of the reverberation curve are used. This is illustrated by the graph below:
To calculate the Early Decay Time (EDT), the time taken for sound to decrease by 10dB is used and multiplied by a factor of six. The EDT is known as the “early reverberation time” and is considered to better reflect how we perceive the reverberance in the room.
The descriptors T20 and T30 are usually called “late reverberation times” as they measure the later parts of the curve.
When calculating T20, the time taken for the sound to decay by 20dB is used and is trebled to give the reverberation time. It should be noted that the evaluation does not start until after the sound level has already fallen by 5dB.
When calculating T30, the time taken for the sound to decay by 30 dB is used and is doubled to give the reverberation time. As with T20 calculations, the evaluation does not start until after the sound level has already fallen by 5 dB.
If the reverberation curve is straight, the EDT, T20, T30, will all produce the same value. However, the reverberation curve is usually not straight (shown by a dashed line on the graph), which means that the descriptors will differ.
The room volume, room shape, and the amount of sound absorbing material present all have an effect on the reverberation time.
Sound Absorption Coefficient
The sound absorbing properties of a material are expressed by the sound absorption coefficient, α, as a function of the
frequency. α ranges from 0 (total reflection) to 1.00 (total absorption).
Time (secs)
So
un
d p
res
su
re l
ev
el
(dB
)
Acoustic Design for Inpatient Facilities in Hospitals Glossary and definitions
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xviii
Sound Absorption Class
In accordance with international standard EN ISO 11654, the absorption classes are designated A-E, where absorption class A has the highest sound absorption. The graph below illustrates the difference in properties of each class.
Sound absorption table
Frequency (Hz)
1. Absorption class A
2. Absorption class B
3. Absorption class C
4. Absorption class D
5. Absorption class E
6. Unclassified
Reflective building materials have low absorption coefficients (α), for example plastered walls have a value as low as α=0.02. Sound absorbing materials have a relatively high absorption coefficient, for example some ceiling tiles can have value as high as α=0.95 at some frequencies.
Ab
so
rpti
on
co
eff
icie
nt
(α)
Acoustic Design for Inpatient Facilities in Hospitals Abstract
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Abstract
There is an increasing body of research into the acoustic environment of hospitals which provides
evidence of the detrimental effects of noise on the well being and comfort of patients and on staff, and
of a significant rise in hospital noise levels in recent years. Much of this evidence has focused on
specific areas of healthcare such as critical care and operating theatres, with comparatively few
studies carried out within general inpatient wards and in UK hospitals.
The current study aims to investigate, through objective and subjective surveys, the noise climate and
acoustic design within general inpatient facilities in the UK, and their influence on the acoustic comfort
of patients and staff. Noise and acoustic surveys have been carried out in six inpatient wards in three
major UK hospitals, with corresponding questionnaire surveys of staff and patients.
Noise measurement data has been analysed to build up a comprehensive understanding of the
contributing factors to noise in both single room and multi-bed patient accommodation, and at the
main ward nurse stations. Comparisons are made between patient accommodation types; medical
and surgical wards; building construction types; ward layouts; and finishes. The potential impact of the
design for infection control on acoustic comfort is also examined.
Patient and staff perceptions of noise are investigated, with the identification of the most annoying
and disturbing noise sources. Attitudes to noise and factors such as age, length of stay, bed location
and length of service are considered where appropriate.
The problem of hospital noise in inpatient wards is found to be very complex in nature, with many
different factors affecting the noise climate. The study concludes that a multi-faceted approach is
required if any significant improvement is to be achieved. This should be centred on three main areas
(i) optimising the acoustic design of the ward, (ii) minimising the disturbance caused by equipment in
use on the ward and (iii) modifying the behaviour of those on the ward. Discussion of these areas is
provided and potential areas of noise control investigated. The observational culture of nursing in UK
hospitals is also considered in relation to ward design.
Two further pieces of work have been carried out in addition to the main study. The first investigates
the effects of changing a non acoustic suspended ceiling for one with good acoustic properties. Noise
levels and reverberation times prior to and after this change are measured and improvements found.
The second piece seeks to validate an estimation method for reverberation times in occupied spaces.
Using noise data captured during the main study, the estimated data is found to demonstrate similar
accuracy to standard measurement techniques, and as such the method could potentially be used to
provide reverberation time estimates in occupied areas where real time measurements are not
practical or possible.
Acoustic Design for Inpatient Facilities in Hospitals Introduction
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2
Introduction
1.1. Background
Concern about noise in healthcare is not a recent phenomenon. In her book Notes on Nursing
(Nightingale, 1860), first published over 150 years ago, Florence Nightingale devoted an entire
chapter to noise and its negative effects. She warns… ‘Unnecessary noise, then, is the most cruel
absence of care which can be inflicted on the sick and well.’
Research into the subject area of hospital noise is surprisingly diverse, with Ulrich et al (2004) citing
no less than 130 studies which focus on the subject. A clear trend of rising hospital noise since the
1960’s has been identified by Busch-Vishniac et al (2005), with average increase in noise levels per
year of 0.38 dB during the day and 0.42 dB at night. This increase in noise levels appears to be
universal in nature, with many international studies showing similar trends.
There is also increasing evidence of the detrimental effects of noise on patient wellbeing and on staff,
with noise induced stress being linked to burnout of critical care nurses (Topf and Dillion, 1988).
Studies have also linked noise levels to patient recovery rates (Fife and Rappaport, 1976) and
associated improvements in acoustic design with reductions in patient re-admission rates (Hagerman
et al, 2005). It should be noted, however, that much of the evidence concerning the impact of noise on
patients and staff is focused on a small number of frequently cited studies.
A review of the literature has found that research into hospital noise has tended to concentrate on
busier areas within hospitals, such as critical care units, intensive care units and operating theatres,
with limited research carried out in inpatient wards. Patients in inpatient wards are generally
recovering from either a severe infection or from surgery, and so require restful conditions that are
beneficial to their recovery. Research on the impact of noise in this area is felt to be of at least equal
importance to research into noise in critical care areas.
1.2. Aims and objectives
The aim of this study is to provide a comprehensive insight into the noise climate in inpatient hospital
wards. The research involves both objective measurements which help build up an understanding of
noise levels and the sources of high level noise; and questionnaire surveys of staff and patients on
the wards, which explore their perceptions of noise. Six inpatient wards in three major hospitals are
the subject of the study, with a mixture of medical and surgical wards and types of building stock.
Hospital buildings of differing ages, construction type, ward design, and finishes are all considered.
The findings of the study will help to inform the decision making process in both new building design
and the refurbishment of existing wards, and to provide general advice around the choice of ward
Acoustic Design for Inpatient Facilities in Hospitals Introduction
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3
equipment and technological systems to be commissioned. The findings also enable a critical review
of current standards to be carried out to ascertain their applicability in relation to occupied buildings.
1.3. Overview
This thesis consists of 12 chapters. Chapter 2 discusses relevant guidance and standards for
healthcare buildings and is followed by an extensive literature review in Chapters 3 and 4. The
findings of these three chapters inform the study methodology which is discussed in Chapter 5 and is
trialled during the pilot study detailed in Chapter 6. The main study locations and results of the
subsequent objective and subjective studies are discussed in Chapters 7 and 9, with a further overall
analysis of these provided in Chapter 11. A full discussion of the study findings in relation to noise
control are provided in Chapter 12. Chapters 8 and 10 are concerned with the results of a ceiling
change carried out in one particular ward, and the validation and use of a reverberation time
estimation method for occupied spaces.
In order to understand the role of acoustic guidance documents and standards in healthcare
buildings, a review is carried out in Chapter 2. Specific guidance on the acoustic design of healthcare
buildings was found to exist as early as 1966, and the changes to standards over time are
considered. Comparisons with European standards are made; the World Health Organisation
guidelines are assessed; and specific design criteria in relation to control of infection on hospital
wards is discussed. In relation to this study, which is concerned with occupied buildings, the
relevance of much of the documentation in this chapter is found to be minimal.
Chapters 3 and 4 aim, through critical evaluation, to build up a thorough understanding of previous
research carried out in the field of hospital noise and acoustic design. For the purposes of clarity
these chapters are divided into a number of categories: noise measurement studies; sleep studies;
the effects of behaviour modification on hospital noise; the effects of room acoustic design
modifications on hospital noise; the effects of noise on healthcare staff; and the effects of noise on
patients. Within each category a number of papers are summarised and some critical appraisal is
made of methods used where appropriate. Discussion of the study findings, design limitations and
areas found to be lacking in research is provided.
Conclusions drawn from the literature review in Chapters 3 and 4 were seminal in informing the
design of the study. Chapter 5 outlines the aims and objectives of this study and provides further
detail of the objective and subjective survey methods used. The preliminary work involved in obtaining
ethical approval and the necessary permissions to carry out the study within occupied ward
environments are also discussed.
To trial the study methodology, a pilot study was carried out in a post surgical inpatient ward at Great
Ormond Street Children’s Hospital, London. Chapter 6 discusses the considerations required when
working in a healthcare environment, including the appropriate location of measurement equipment
Acoustic Design for Inpatient Facilities in Hospitals Introduction
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4
and the distribution of questionnaires. Detailed results of the objective noise level measurements are
presented and the subjective perceptions of the noise climate of both patients and staff examined.
The main study was undertaken in two inpatient wards at Bedford Hospital and three inpatient wards
at Addenbrooke’s Hospital, Cambridge. The results from these study wards are reported in Chapters
7 and 9 respectively. Details of the objective measurements made in each ward are discussed and
the subjective perceptions of staff and patients are compared. Further analysis of these results are
presented in Chapter 11, which considers factors affecting noise levels, and staff and patient
perceptions.
Two further pieces of work were carried out in addition to the main study. Planned refurbishment
works were due to take place in the medical ward at Bedford Hospital, which had been the subject of
objective and subjective surveys. The works were scheduled to start several weeks after the end of
the study data collection, and this enabled a ceiling intervention study to be carried out in which non
acoustic ceiling tiles were replaced by tiles with good acoustic properties. Noise levels and
reverberation times were investigated prior to and after this change and the results are reported in
Chapter 8.
The second piece of work was the validation of a reverberation time (RT) estimation method. This
method, known as the Maximum Likelihood Method, was developed by the University of Salford for
use with recorded speech or music. Since making RT measurements in occupied hospital wards is
not practical using standard methods, an alternative method to estimate the RTs of occupied wards
was considered to be extremely useful. Validation of this method was carried out using data captured
from the study wards and is discussed in detail in Chapter 10.
Chapter 12 summarises the findings of this study in relation to noise control in inpatient hospital
wards; the applicability of standards to occupied hospital buildings; and the usefulness of particular
acoustic measurement parameters in the reporting of hospital noise. Study conclusions and
recommendations for further work are discussed in the final chapter of this thesis.
Acoustic Design for Inpatient Facilities in Hospitals Acoustic standards and guidance
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5
2. Acoustic standards and guidance
2.1. Introduction
This chapter reviews the history of guidance relating to acoustic design of UK healthcare facilities up
to the present time. The differences between UK and European guidance are explored, and the
relevant section of the World Health Organisation ‘Guidelines for Community Noise’ summarised.
The final section presents further discussion on other aspects affecting acoustic design in
healthcare.
2.2. UK design guidance
In the UK, design of healthcare buildings is governed by guidance published by the Estates and
Facilities Division within the Department of Health. Essentially, the guidance falls into the following
two categories:
� Health Building Notes (HBN) which provide advice to project teams designing and planning
new buildings and refurbishing existing buildings.
� Health Technical Memoranda (HTM) which provide estates and facilities professionals with
guidance on the design, installation and running of specialised building service systems.
It appears that some guidance was available as early as 1966, with information on noise control
provided in the Ministry of Health Hospital Design Note 4: Noise Control (Her Majesty’s Stationery
Office, 1966). As with more recent guidance this design note provided general advice on plant noise,
the performance of internal partitions and external wall construction. More surprisingly, suggestions
for effective noise control in occupied wards were given for a variety of items such as ‘quiet curtain
tracks’; hospital trolleys with good quality rubber tyred wheels; the use of steel sinks coated with
rubber on the underside to minimise noise; and the suggestion that TVs in multi-bed wards should be
wired through patients’ headphones only.
For the purposes of this review, the three most recent guidance documents affecting acoustic design
of healthcare buildings are examined in further detail. These are HTM 2045 Acoustics: Design
Considerations (NHS Estates, 1996), HTM 56 Partitions (NHS Estates, 1997) and HTM 08-01
Acoustics (The Stationary Office, 2008).
HTM 2045 Acoustics: Design Considerations (NHS Estates, 1996) contained partition performance
requirements as well as advice on many other aspects of acoustic design including mechanical
services noise, impact noise, vibration, façade sound insulation, and reverberation times. Not only
did the guidance provide specification of acoustic design criteria, it also provided information on the
sources of noise and provision of noise control, and an eleven page section on the principles of
Acoustic Design for Inpatient Facilities in Hospitals Acoustic standards and guidance
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6
acoustics. At a total 53 pages in length, it was considered by some as rather impractical (Popplewell,
2008).
HTM 56 Partitions (NHS Estates, 1997) provided general design guidance on the construction and
performance of internal partitions, with some specific performance criteria to ensure adequate
privacy between rooms in a healthcare setting. The partition performance criteria set out in this
guidance document were less stringent than those provided in HTM 2045 as they were specified in
terms of sound reduction, with no implied requirements for flanking control or need to pay attention to
junction detailing.
Confusingly, HTM 2045 was intended to take precedence over HTM 56, although it was published a
year earlier. However, in the construction industry both guidance documents were considered to be
current. Many healthcare buildings were built to the less comprehensive and less stringent criteria
set out in HTM 56, as this was considered to be a less expensive option. To end this confusion HTM
56 was finally revised in 2005. All guidance on acoustic performance was removed and the standard
was re-written to refer to HTM 2045, which was itself superseded in 2008 by HTM 08-01, and is
discussed in the following section.
2.2.1. HTM 08-01
The latest acoustic design guidance ‘HTM 08-01 Acoustics’ was published in 2008 (The Stationary
Office, 2008) and superseded HTM 2045.
Popplewell (2008) explained the drivers for change behind the latest standard and discusses some
of the difficulties associated with the implementation of HTM 2045. A number of examples were
provided by the author to illustrate these difficulties, following his own experiences of working with
several large Private Finance Initiative healthcare projects, and are shown below.
� The reverberation time criterion was felt to be unrealistic in areas where absorptive finishes
were not appropriate for the reasons of infection control, for example in an operating theatre.
� The building services noise criterion was felt to be impractical due to the need for dedicated
air handling systems in specific areas.
� The impact sound performance requirements of HTM 2045 could not be guaranteed by
contractors.
A number of aims of the new standard were suggested by Popplewell (2008), with the emphasis on
creating a simple, practical and effective standard. HTM 08-01 was designed to:
� simplify and shorten the text of HTM 2045
� make sure recommendations were practical and appropriate
Acoustic Design for Inpatient Facilities in Hospitals Acoustic standards and guidance
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� clarify aspects which were considered to be open to misinterpretation in the previous
standard
� remove specific limits where they either imposed unnecessary costs or where they were
unachievable from a practical perspective
� allow for the incorporation of new technologies
As published, the HTM 08-01 is indeed a more streamlined version of the previous standard. It
recommends acoustic criteria for both noise intrusion and mechanical services noise. Footfall, plant
vibration and internal sound insulation requirements are also considered. Examples are shown in
Tables 2.1 & 2.2.
Table 2.1 Example of criteria for intrusive noise from external sources, HTM 08-01
(The Stationary Office, 2008)
Table 2.2 Example of criteria for internal noise from mechanical and electrical services, HTM 08-01
(The Stationary Office, 2008)
Several matrices are provided to simplify the calculation of the internal sound insulation
requirements. These matrices take into consideration the privacy requirements and the potential
noise generated within each room type. Tables 2.3 and 2.4 provide examples.
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Table 2.3 Example of sound insulation parameters of rooms, HTM 08-01
(The Stationary Office, 2008)
Table 2.4 Example of sound insulation ratings (dB, DnT,w) to be achieved on site, HTM 08-01
(The Stationary Office, 2008)
One of the main differences between this and the previous standard is the lack of specific guidance
on room acoustic design. HTM 2045 specified reverberation times for rooms of different functions
with volumes less than 1000 m3, as shown in Figure 2.1, where room types A, B and C are
consulting rooms, multi bed wards and bathrooms respectively.
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Figure 2.1 Recommended RTs for different room functions and volumes,
HTM 2045 (NHS Estates, 1996)
The latest standard is much more general, providing guidance regarding the amount of acoustic
absorbency used, but does not include precise guidance on room reverberation times, advising that a
‘reverberation-time criterion should be agreed depending on the specific requirements for use of the
space’.
The guidance acknowledges that the use of acoustically absorbent materials ‘can have a dramatic
effect on the acoustic comfort in a room’ and is particularly necessary where speech intelligibility is a
requirement. It states that sound absorbent treatment should be used in all areas, including
corridors, and recognises that there may be issues surrounding the use of sound absorbent
materials where ‘cleaning, Control of Infection, patient safety, clinical and maintenance requirements
allow.’
The guidance suggests that the most appropriate area for acoustically absorbent material should be
a ceiling, with the minimum absorption area equivalent to 80% of the area of the floor when using a
Class C absorber (see Glossary).
Occupied hospital buildings
It is important to note that HTM 08-01 is applicable to a newly built or refurbished unoccupied
healthcare facility, where specific systems can be measured alone. Most of the values specified
however cannot be compared with measurements made in an occupied building, where systems
cannot be isolated. Nevertheless, there is some general guidance which is relevant for occupied
buildings and is listed below:
Medical Equipment
The standard states that ‘ideally it should be chosen so that it does not adversely affect the use of
the surrounding space’ and that ‘quiet equipment should be chosen.’
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Nurse-call Systems
Guidance is given regarding the choice of nurse-call systems to the effect that ‘nurse-call systems
can disrupt sleep; therefore non-audible systems should be considered; especially at night.’ Also it is
suggested that ‘audible alarms intended for staff should be located such that they cause minimum
disruption to patients.’
The standard also contains a checklist for the most important acoustic issues. Some internal ‘fit-out
equipment’ and ‘management issues’ listed are relevant when considering noise levels in occupied
wards, and the relevant extract of the checklist is shown in Table 2.5.
Table 2.5 Extract from Chapter 8 ‘Checklists’, HTM 08-01 (The Stationary Office, 2008)
2.3. European healthcare design guidance
Bergmark and Janssen (2008) compiled an overview of international standards focussing on those
portions which dealt with room acoustics within healthcare buildings. Comparison was made
between standards from Sweden, Germany, Finland, Norway, UK, Denmark and The Netherlands.
The UK was found to be the only country with a specific healthcare guidance document. Sweden,
Finland, Norway and Denmark have healthcare specific sections within wider guidelines, whereas
Germany and the Netherlands use general workplace criteria.
The study noted that the UK standard, HTM 08-01, was the only standard which did not provide
specific guidance on either room reverberation times or speech intelligibility. It was also noted that,
with the exception of UK and Denmark, ‘comfort classes’ were mentioned in each of the standards.
These comfort classes aim to define the level of acoustic comfort for the user by using certain
acoustic parameters such as reverberation times and levels of building services noise.
Table 2.6 provides a summary of the seven European standards and guidelines reviewed.
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Table 2.6 Standards and guidelines for healthcare design in Europe (Bergman and Janssen, 2008)
Table 2.7 summarises the acoustic parameters specified by the standards for the purposes of
acoustic room comfort.
Table 2.7 Acoustic parameters (Bergman and Janssen, 2008)
2.4. World Health Organisation guidelines
The most recent edition of the World Health Organisation (WHO) Guidelines for Community Noise
was published in 1999 (Berglund et al, 1999). The guidelines seek ‘to consolidate actual scientific
knowledge on the health impacts of community noise and to provide guidance to environmental
health authorities and professionals trying to protect people from the harmful effects of noise in non-
industrial environments’.
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In relation to noise in hospitals, the guidelines state that ‘the critical effects of noise are on sleep
disturbance, annoyance and the communication interface, including interference with warning
signals’. Values of LAeq are provided for day time, which is listed as 16 hours from 07.00 – 23.00. LAeq
and LAmax values are provided for night time, which is listed as eight hours from 23.00 – 07.00, with
LAmax values measured on a fast setting. A summary of the guidelines is shown in Table 2.8.
Table 2.8 World Health Organisation guidelines for hospital wards and treatment rooms
Specific Environment Critical Health
Effects LAeq (dB) Time Base (Hours) LAmax (dB)
Hospital, ward rooms,
indoors Sleep disturbance 30 Night time (8 hours) 40
Hospital, ward rooms,
indoors Sleep disturbance 30
Day time and evenings
(16 hours) -
Hospital, treatment rooms,
indoors
Interference with
rest and recovery
As low as
possible
The guidelines also suggest ‘since patients have less ability to cope with stress that the LAeq level
should not exceed 35 dB in most rooms where patients are being treated or observed’.
2.5. Control of Infection
In the UK, Healthcare-Associated Infection (HCAI) has become an increasingly high profile issue
over recent years. The result has been increased pressure on UK hospitals to clean more frequently,
more thoroughly and with stronger cleaning agents. Several guidance documents have been
produced which provide advice on the use of suitable materials to withstand the new cleaning
regimes. These materials include flooring, wall coverings and ceiling finishes, the most relevant to
the current study being the use of acoustic ceiling tiles. The relevant paragraphs of each document
are explored in the sections below.
‘Control of Infection teams’ have been set up in all hospitals to make general decisions in relation to
hospital HCAI policies. These teams interpret the guidance documents in different ways, some more
vigorously than others.
2.5.1. HTM 60
HTM 60 (NHS Estates, 2005) deals with all aspects of suspended ceilings, including fire performance,
ceiling tile composition, wind loading, and details of grid construction. Only two sections are of
relevance in terms of HCAI and these detail the physical characteristics of the ceiling tiles to be
installed, and provide advice on hygiene and cleaning.
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The guidance divides room types into six different categories and lists suitable ceiling finishes to be
used for each. For example, Category 1 applies to operating theatres; Category 4 applies to multi-bed
bays or single patient rooms; and Category 5 to storerooms. Table 2.9 shows that within a Category 4
room, all ceiling types may be used, whereas in a Category 1 room only smooth, imperforate, jointless
ceilings are advised.
Table 2.9 Recommended ceiling characteristics for hospital room types, HTM 60
(NHS Estates, 2005)
In the section entitled ‘Hygiene and cleaning’, the guidance discusses a new ‘model cleaning contract’
for hospitals which, it states, has three key aspects:
1. The National Standards of Cleanliness. This document discusses possible measures for
HCAI cleaning and disinfection.
2. NHS Cleaning Manual. This manual sets out best practice methods for cleaning.
3. Cleaning frequencies. These should be determined to address the element of risk identified
within the National Standards of Cleanliness and should take into account any further advice
and guidance in the model cleaning contract and the NHS Cleaning Manual.
At the time of writing, the NHS Cleaning Manual is no longer readily available, even though HTM 60 is
still current and has not been amended to reflect this.
2.5.2. National Standards of Cleanliness for the NHS
There are several relevant sections in the National Standards of Cleanliness for the NHS (NHS
Estates, 2001) which list the cleaning requirements and cleaning frequencies for walls, skirting boards
and ceilings.
The guidance states that ‘internal and external walls and ceilings are to be free of dust, grit, lint, soil,
film and cobwebs’ and that ‘walls and ceilings are free of marks caused by furniture, equipment or
staff’. Further information can be seen in terms of cleaning time scales for walls, skirting boards and
ceilings.
Table 2.10 provides information on cleaning frequencies by area type.
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Table 2.10 Cleaning frequencies in terms of area type priority
Priority Frequency Time Frame for Rectifying
Problems
A Constant, cleaning critical Immediate
B
Frequent, cleaning important and requires
maintaining 0-48 Hours
C
Regular, on a less frequent scheduled basis
and as required in between 2-7days
D Infrequent, or on a scheduled or project basis 1-4 weeks
Priority A applies to operating theatres, ICU and similar units and Protective Isolation Areas.
Priority B applies to sterile supply areas, A&E, pharmacy, general wards and daily activity areas,
rehabilitation areas, residential accommodation, pathology, kitchens, outpatients’ clinics, treatment
and procedure rooms, cafeteria and public thoroughfare.
Priority C applies to general pharmacy, laboratories, mortuary, medical imaging, waiting rooms and
administrative areas.
Priority D applies to non-sterile supply areas, record archives, engineering workshops, plant rooms
and external surrounds.
2.5.3. HFN 30 Infection Control in the built environment
HFN 30, Infection Control in the Built Environment – Design and Planning (NHS Estates, 2002) states
that ‘if the burden of healthcare-associated infection is to be reduced, it is imperative that architects,
designers, and builders be partners with healthcare staff and infection control teams when planning
new facilities or renovating older buildings’.
In relation to ceilings, the guidance stresses the importance of high quality finishes and recommends
that ceilings with smooth, hard, impervious surfaces are installed in theatres and isolation rooms. The
guidance warns that during maintenance work, suspended ceilings can allow dust to fall onto the area
below and therefore this type of ceiling should therefore be avoided in isolation rooms, operating
theatres and treatment rooms. There is no mention of ceiling types for general inpatient wards.
2.6. Discussion
The latest UK design guidance has been simplified to be as practical as possible. Popplewell (2008)
mentions that in particular the internal sound insulation matrices have been well received by
contractors who have found them simple to use and understand. Design guidance of this type aims
to go some way to minimising external noise break-in, plant noise, and noise transmission between
rooms and when put into practice appears to be successful in these areas, as shown by Boulter
(2007).
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The relevance of the HTM guidance to the current study is fairly limited, as the study is investigating
noise levels in occupied wards. Only guidance regarding the use and choice of a number of internal
systems has some application.
The omission of specific guidance relating to reverberation time values or target values for speech
intelligibility potentially provides designers and contractors with a ‘get out’ option, which is simply to
ignore these criteria completely. This could have a negative impact on noise levels and acoustic
comfort of wards.
Comparison of the UK guidance with six different European design guidelines indicates that it is
considered important by those countries to specify at least one measure of acoustic comfort. This
again suggests that this omission in the latest HTM could be detrimental to the acoustic environment
in UK hospitals.
The noise levels suggested by the World Health Organisation are relevant in terms of occupied
wards. It would, however, seem that the validity of these levels is questionable as all noise studies
referenced (see Chapter 3) have found levels to be above the WHO guidelines in general.
Guidance documents are available which provide advice on the types of ceiling finishes required and
the cleaning frequencies. The documents are open to interpretation and therefore may be interpreted
more or less stringently at different locations. Some inconsistencies do exist, with one major
guidance document referenced, no longer available.
With regards to the type of acoustic materials for use in areas where there are concerns about HCAI,
no clear design guidelines appear to be available. Acoustic ceiling tiles which will withstand
bleaches and high pressure washing are readily available on the market. It is important that not only
are contractors and designers made aware of these products, but also the hospital Control of
Infection teams, who have an increasing influence on the internal finishes used. Without this
knowledge the use of non acoustic ceiling tiles may become more prevalent, having a detrimental
effect on the acoustic comfort of a room.
2.7. Conclusions
It has been shown that the UK guidance is on the whole less stringent than guidance in other
European countries or the WHO guidelines. In the current study objective levels measured are
compared with current guidelines where appropriate. The following two chapters review previous
research on hospital noise and its effects on staff and patients. Many of the studies reviewed show
that current guideline values are exceeded.
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3. Previous research on hospital noise
3.1. Introduction
There has been a significant body of research into various aspects of hospital noise and acoustics in
the past 50 years. This chapter aims, through critical evaluation, to build up a thorough
understanding of previous research carried out in the field of hospital noise and acoustic design. For
the purposes of clarity this review is divided into four categories: noise measurement studies; sleep
studies; the effects of behaviour modification on hospital noise; and the effects of room acoustic
design modifications on hospital noise.
Within each category a number of papers are summarised and some critical appraisal is made of
methods used where appropriate. Discussion of the study findings and design limitations are provided
at the end of each section.
3.2. Noise measurement studies
The hospital environment is an extremely complex one, consisting of many different areas, including
Accident and Emergency (A&E) departments, operating theatres, intensive care units (ICUs) and
general inpatient wards. In each area, different activities are taking place with patients requiring
different levels of care.
Much of the available literature investigating noise levels in hospitals concentrates on specific
measurement locations. It appears that many of these locations were chosen because of the
perception that they were more ‘noisy’. This makes it difficult to build up an overall picture of the noise
climate across all areas of the hospital.
A large review of previous studies dating from 1960 was carried out by Busch-Vishinac et al in 2005.
In order to identify whether a trend in hospital noise exists, the authors compiled data from all
comparable studies post 1960 which listed LAeq noise measurement values. Although it was
acknowledged that there were some discrepancies in the data (for example, no indication of sampling
rates or the period of time averaging), the study yielded some interesting results.
The findings were three-fold:
i. Not one single study showed a hospital which complied with the WHO guidelines for hospital
noise, raising the question of the validity of these particular guidelines.
ii. The study showed less variation in results than was expected. This was surprising given that
the data was gathered from widely differing sources – different types of medical units and
hospitals situated in a number of different countries throughout the world. It led the authors to
conclude that the problem of hospital noise is a universal one.
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iii. A clear trend was shown for rising hospital noise since 1960. The data showed an increase of
0.38 dB per year for day time levels and 0.42 dB per year for night time levels, with a rise in
measured LAeq values from 57 dB in 1960 to 72 dB in 2005 during day time hours, and from
42 dB in 1960 to 60 dB in 2005 during night time hours.
Figures 3.1 and 3.2, reproduced from Busch-Vishinac et al (2005), show the A-weighted
equivalent day and night sound pressure levels as a function of year of study publication. The
error bars indicate that data was given as a range spanned by the error bars.
Figure 3.1 LAeq values measured in hospitals during day time hours as a function of the year of
study publication. (Busch-Vishinac et al, 2005)
Figure 3.2 LAeq values measured in hospitals during night time hours as a function of the year of
study publication. (Busch-Vishinac et al, 2005)
The remainder of this section focuses on the more recent relevant studies of hospital noise, which are
summarised in Table 3.1.
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In 1996, McLaughlin et al considered noise levels in a cardiac ICU at the Royal Group of Hospitals,
Belfast, and concluded that they were consistently higher than those stipulated in the WHO
guidelines. LAeq values for the measurement period were found to be above 60 dB at all times and
LAmax values greater than 80 dB were measured as early as 5am.
Two studies of noise in hospitals in the US were published in 1999 and 2001. Holmberg and Coon
(1999) examined noise levels within adult and adolescent day rooms in a state psychiatric hospital in
Indiana, and found levels to exceed those measured in other studies of medical, surgical and
intensive care units. Noise levels in A&E departments in four Phoenix hospitals were measured by
Buelow (2001), who concluded that levels were higher than those in which an individual can
comfortably work. The levels were thought to approach or exceed those that can cause feelings of
annoyance.
Tsiou et al (2008), recorded sound levels during surgical procedures carried out in the operating
theatres of nine Greek hospitals. Comparisons between sound levels measured during non-
orthopaedic surgery and orthopaedic surgery were made. This extensive study showed orthopaedic
surgery to be a particularly lengthy, noisy process and recommended that personnel make use of
hearing protection and undergo regular audiometric tests. Sources of noise were identified and their
sound levels noted.
3.2.1. Limitations of noise measurement studies
Measuring noise within a healthcare setting introduces a number of challenges. Patients are in
hospital because they require care; staff are busy and often working beyond their capacity. To take
measurements in a non-intrusive manner without causing annoyance or suspicion is often difficult.
The Hawthorne Effect
One known issue when undertaking a measurement study in an occupied building, is the reaction of
those people in the vicinity of the measurement equipment. If it becomes known that a study is being
undertaken, people may react in a way that might affect the results. This phenomenon was identified
by Henry A. Landsberger in 1955 when analyzing results from a set of experiments carried out from
1924 – 1932 at the Hawthorne Works, and has become known as the ‘Hawthorne Effect’ (cited by
Bailey and Timmons, 2005). Landsberger defined the Hawthorne effect as ‘a short-term improvement
caused by observing worker performance’.
The Hawthorne effect was thought by Bailey and Timmons (2005) to be significant in their study of
noise levels in paediatric ICU in a large UK teaching hospital. It was noted that once
Table 3.1 Measurement data from studies cited in Section 3.2
Author Date Location Measurement
Period Measured Levels
McLaughlin et al 1996 Cardiac ICU, Belfast 24 hr
LAeq > 60 dB, LAmax > 70 dB (for measurement period) , LAmax =100.9 dB
Holmberg and Coon
1999
State psychiatric
hospital, US
36.5 hrs in total at
different times of day
Mean (arithmetic) = 75.7 dBA, LAmax = 92.5 dB ; Sound peaks consistently between 85 and 90 dB
Buelow et al
2001
A&E departments at 4
hospitals in Phoenix, US
16.00 – 20.00
(4 hours)
LAeq = 69.1 dB, 70.1 dB, 71.1dB, 65.0 dB
LAmax = 76.6 dB, 73.4 dB, 73.0 dB, 75.2 dB
Bailey and Timmons
2005
Paediatric ICU in a UK
teaching hospital
24 hr
Loudest voices measured between 68 and 72 dB; General conversation measured between
50 and 65 dB; Equipment alarms measured between 65 and 83 dB
Busch-Vishinac et al 2005 5 locations within the
Johns Hopkins Hospital
3 x 24 hr
measurements at
each location
LAeq : 50 – 60dB (PICU showing the highest noise levels)
Kracht et al 2007
38 operating theatres at
the Johns Hopkins
Hospital, Maryland, US
24 hr
Orthopaedic surgery LAeq = 66 dB
Neurosurgery, urology, cardiology, gastrointestinal surgery LAeq : 62 - 65 dB
Neurosurgery and orthopaedic surgery LAmax >100 dB for over 40% of the time, with peaks >120 dB
Orellana et al 2007
Adult A&E at the Johns
Hopkins Hospital
24 hr Triage Area LAeq : 65 – 73 dB
General A&E LAeq : 61 – 69 dB
Tsiou et al 2008
Operating theatres at 9
Greek hospitals
During 43 different
procedures
Pre-surgical LAeq : 61.1 - 78.2 dB, LA90 : 49.2 - 61.2 dBA, LAmax : 83.6 - 99.4 dB
Surgical LAeq : 57.4 - 70.1 dBA, LA90 : 48.2 - 58.7, LAmax : 84.7 - 100 dB
Post-surgical LAeq : 60.5 - 74.1 dBA, LA90 : 49.7 - 60.7, LAmax : 78.8 - 106 dB
Connection / disconnection of gas supply responsible for loudest sound peak of 106 dB
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members of staff became aware of the study, they changed their behaviour accordingly. The
researchers found that the female staff lowered their voices and made an effort to keep noise levels
down; whereas the male staff made deliberate attempts to make noise by shouting at the microphone
and banging equipment (these impulsive noises were ignored in the results).
It has been shown that it is possible to minimise the influence of the Hawthorne effect. For example,
in the study of noise in a cardiac ICU by McLaughlin et al (1996), discussed in the previous section,
the SLM was concealed in a dummy box which had time, temperature and humidity displays. It was
perceived that these displays were sufficient to satisfy the curiosity of the staff regarding this new
piece of equipment placed in their work environment.
Similarly, Kracht et al (2007), who measured operating theatre noise at the Johns Hopkins Hospital in
Baltimore, placed their sound level meter (SLM) so that it did not interfere with the operations. It was
wrapped in a plastic bag to avoid contamination and this may have made the meter less conspicuous.
It was observed that the staff were generally unaware that the meter was present and so did not
attempt to control conversation levels or the playing of music during the operations.
Acoustic inconsistencies and omissions
Partially due to the restrictions that are inherent in working within an occupied ward, it was found that
many of the studies reported measurements in ways that often prevent study comparison. It was also
noted that many of the studies were undertaken by healthcare professionals with little or no knowledge
of acoustics. In a number of studies certain acoustic criteria were not considered, or important key
elements were omitted from the report.
Further details of typical omissions and inconsistencies are given below:
i. Calculation of the time averaged sound pressure level (SPL)
Some of the studies appeared to calculate the average SPL recorded over a period of time
arithmetically, rather than logarithmically. This method of time averaging yields a lower value
and therefore levels may not be comparable with those studies that provide a logarithmically
averaged LAeq,T value.
ii. Equipment Sampling Rates
Many studies do not state the sample rate settings used on the SLM. For some
measurements this setting can make a difference and therefore studies which do not specify
this cannot be used for comparison purposes.
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iii. Unspecified, linear or A-weighted measurements
Measurements reported in some studies were either unspecified or listed as linear un-
weighted values. Without frequency band data, conversion of linear to A-weighted values for
comparison with other studies is not possible.
iv. Only minimum and maximum values reported
Some studies did not list either background levels of the noise or time averaged noise levels,
choosing only to list maximum and minimum values. Without time averaged measurements it
is impossible to put maximum and minimum values into context
v. The position of the sound level meter whilst undertaking measurements.
Some studies were concerned with the noise levels experienced by the patient and positioned
the sound level meter by the bed head, while other studies measured the general sound levels
within an area and in some cases positioned the meter by the nurse station. Alternatively
some studies took readings in a number of different areas to build up an overall picture of the
‘noise climate’. On occasions this positioning information was omitted from the paper
completely.
3.2.2. Understanding the overall hospital noise climate
Due to the singular nature of many of the studies, it has been difficult to build up a full picture of noise
within a hospital as a whole. Measurements are provided for specific settings, but have no context in
which they can be compared with other areas in the same hospital.
In their wide-ranging study, Busch-Vishniac et al (2005) took measurements in five different locations
within the Johns Hopkins Hospital in Baltimore, USA. The locations included a paediatric ICU, an adult
medical / surgical ward and a ward for immuno-compromised patients. The locations were in a variety
of buildings of differing ages (the most recent having being built in 1999, the oldest in 1950). To build
up a full picture of the noise climate in each location, measurements were made in patient rooms,
hallways and at nurse stations.
The study found that there was little difference between the sound levels measured in different
locations, although it did cite hallways as the noisiest areas, followed by nurse stations and patient
rooms. The average recorded levels exceeded the levels specified by WHO guidelines by 20 dB and
by at least 15 dB for LAmax. The authors expressed surprise that the newer building (where noise had
been a consideration during the design and construction) was not particularly quieter than the older
buildings.
This study also examined the frequency spectra of the measured sound. Analysis of the component
parts of the noise can provide extremely useful information regarding the sources of noise. The
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spectra were found to be similar in shape for each of the locations and the following observations were
made:
� The low frequency noise was almost certainly related to the air handling systems
� Due to the amount of talking observed, the shape of the mid frequency spectrum could easily
be explained.
� The high frequency noise was thought to be predominantly caused by alarms and mobile
medical equipment. The high velocity airflow system was also thought be influential.
To add to this picture of the hospital noise climate, two further studies were conducted at the Johns
Hopkins Hospital:
Kracht et al (2007) measured noise levels in the 38 operating rooms at the Johns Hopkins Hospital.
Noise levels occurring during each type of surgical procedure were captured and frequency spectra
were also analysed. For neurosurgery and orthopaedic surgery, peak levels were found to be above
100 dBA for over 40% of the time. The highest recorded peaks were in excess of 120 dBA. The results
raised two concerns: the potential for hearing loss and the disruption to clear speech communication.
Orellana et al (2007) recorded LAeq measurements within seven different areas of an adult A&E
department. Levels were found to be 5 dB higher than those recorded in other inpatient units within
the hospital, with the triage area of the department found to be the noisiest. The study raised concerns
regarding speech communication without errors, with additional concerns for the medical staff, since
speaking in a raised voice can in itself be tiring.
3.2.3. Identifying noise sources
In addition to building up a picture of the noise climate within a hospital in terms of noise levels, some
studies endeavoured to provide a list of the main sources of noise.
Some earlier studies relied on an individual observer making lists of those sounds which were
perceived to be the loudest. This was of course difficult to later tally with data measurements and
relied on subjective opinion and accuracy of observation. It also introduced the possibility of the
Hawthorne effect as the observer would probably need to inform those around them of their purpose.
However, measuring noise levels during an un-manned study presents a different problem, namely
how to identify the sources of high level noise.
Hodge and Thompson (1990) tackled this problem by making an audio recording of the entire surgical
procedure as well as making measurements with a sound level meter. This allowed sound peaks to be
identified. However, this method introduced more intrusive equipment into a very sensitive area and
also required accurate synchronising of the equipment, potentially leading to later errors. The study
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found that during surgery the main sources of high level noise were the sucker and the ventilator, with
the anaesthetic alarms and intercom also contributing.
In their noise surveys of operating theatres, Kracht et al (2007), reported that it was not possible to link
peak sound pressure levels with specific events (for example the use of a bone saw).
3.2.4. Discussion
The review of the literature on hospital noise levels has indicated that the problem of hospital noise
appears to be universal in nature, with a clear trend of rising noise levels both day and night since
1960. Without exception, all noise measurement studies reviewed found that hospital noise levels
exceeded both the World Health Organisation guidelines and the standards set within their own
particular countries. This finding surely makes the validity of the standards questionable.
The majority of studies evaluated have targeted perceived ‘noisier’ areas of hospital care, with a bias
towards patient noise exposure. Few studies concentrate on inpatient ward noise levels and fail to give
adequate consideration to the working environment for staff.
Some consideration should be given to the potential impact of the Hawthorne effect within the design
of a future study. However, this raises the issue of the ethics of studies undertaken in secret.
Previous studies have failed to build up a robust picture of the noise climate within an entire hospital
ward, with most using only a single microphone position. Measurement intervals also tend to be short
(24 hours or less), with no representative interval established. Identification of noise sources was often
found to be unscientific, with acoustic inconsistencies and omissions in reported data making
meaningful study comparisons difficult.
The new generation of sound level meter may overcome the problem of identification of noise sources
without observers. Due to the large data storage capacity now available, these meters are able to
record a short digital audio file whenever sound levels exceed a certain threshold. The audio files are
automatically synchronised with measured sound levels, and so on playback it is possible to identify
the source and level of a particular sound.
3.3. Sleep studies
Sleep is widely thought to be necessary for the restorative and energy conservation processes (Adam
and Oswald, 1983; Berger and Phillips, 1995), and sleep disturbances have been shown to
exacerbate the pain felt by hospital patients (Raymond, 2001). Many reviewed studies considered the
effects of environmental and medical factors on sleep, but few looked directly at the relationship
between noise and sleep in a hospital environment. This section reviews four studies that were felt to
be relevant to the current study.
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Aaron et al (1996) conducted a study to test the hypothesis that nocturnal (midnight to 6am) sound
peaks would be associated with an increase of EEG arousals from sleep in patients in the respiratory
ICU at the Rhode Island Hospital, Providence, USA. A significant difference was found between the
number of sleep arousals in quiet periods and the number in very loud periods. However, due to the
small sample size of six patients and the differing health factors (which prevented realistic
comparison), the study found only an indirect link between sleep disturbance and environmental noise.
Freedman et al (2001) studied 22 critically ill patients with continuous polysomnography (PSG) to
characterize the sleep-wake patterns and objectively determined the effect of environmental noise on
sleep disruption. This study was deemed to be unique at the time as the measurement output from the
sound level meter was relayed to the PSG so that the results could be simultaneously evaluated.
Findings showed that environmental noise was responsible for 11.5% of overall arousals and 17% of
awakenings, but concluded that noise was not responsible for the majority of sleep fragmentation and
therefore may not be as disruptive as previously thought.
Gabor et al (2003) monitored critically ill patients in an ICU and compared the results with a sample of
healthy, unattended individuals who volunteered to take part in the study in ICU to see the effect of
noise on their sleep quality. The study also investigated the effectiveness of a noise-reduction strategy
by monitoring subjects in a single bed room. All subjects were monitored with continuous and attended
PSG.
This study made some interesting findings:
� Fewer than 30% of arousals and awakenings in the ICU patient group were identifiably due to
noise and patient care activities. This suggested that other elements of a critically ill patient’s
environment should be investigated as causes of sleep disruption, and as with Freedman et al
(2001), this is in contradiction to traditional hypotheses.
� The healthy individuals in the sample slept relatively well in the ICU. Noise was responsible for
the majority of their sleep disruptions, although this was unsurprising, as other potential
interruptions such as patient care activities and respiratory ventilation were not
present.
� A quantitative improvement of sleep in single bed rooms was found, but sleep architecture
was nearly identical.
As with the majority of sleep studies, this study was limited by its small sample sizes.
3.3.1. Modification of room acoustics and its effects on sleep
Berg (2001) monitored the sleep patterns of subjects exposed to different sounds in an acoustically
altered hospital room. PSG monitoring was carried out on twelve healthy subjects between 20 and 25
years old with no prior history of sleeping difficulties. The room was a refurbished former three bed
surgical ward in a Swedish hospital with a suspended ceiling. The ceiling comprised sound reflecting
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tiles during the first two nights of the study. On the third night the tiles were replaced with visually
identical sound absorbing tiles. There were minor differences measured in the SPL before and after
the intervention. The reverberation time was found to decrease by an average of 0.12 seconds (200 to
5000 Hz).
Twelve different sounds of varying frequencies were played at different levels (27 to 58 dBA). The
study found no significant difference in sound induced sleep stage changes, but did find fewer EEG
sleep arousals in the less reverberant room.
This study did not however deal directly with hospital noise. The type of environmental sounds did not
reflect those that patients would be exposed to in a healthcare setting, and the level at which they
were played was not necessarily representative of that found in a hospital. However, the study showed
that the room acoustic design modification appeared to have some effect on sleep quality and as such
is considered to be relevant.
3.3.2. Discussion
Study findings suggest that, contrary to traditional hypotheses, noise is not responsible for the majority
of sleep disturbances of critically ill patients; however with such small sample sizes, no definitive
conclusion is possible.
The large numbers of uncontrollable factors make it extremely difficult to obtain realistic and
comparable data within this category of studies; especially when studying patient groups. Each patient
is unique, with a different physicality, different health issues, and taking differing amounts and types of
medication. Even when considering two healthy individuals, they would sleep differently in the same
environment, and so, with the introduction of so many additional variables, it is very hard to draw
meaningful conclusions.
3.4. The effects of behaviour modification on hospital noise
Human behaviour has been identified as being responsible for a surprisingly large percentage of high
level noise within hospital settings. It appears that through simple methods, at minimal cost, noise
levels can be lowered by making individuals aware of the direct and indirect impact of their actions.
Elander and Hellstom (1995) measured noise levels for routine activities within a neonatal ICU of a
Swedish University hospital. It was found that many of the high levels were attributable to human
behaviour, for example staff laughter, conversation and careless closing of doors, incubators and
drawers.
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As part of the study an education programme was presented to the ICU staff which consisted of three
parts:
� A videotape showing a child's post-operative period (filmed from the child's view-point;
highlighting the child’s reaction to various sounds) - one nurse was surprised to find an infant
wake and start to cry at the sound of her voice.
� Sound level values for various activities were provided to help nursing staff to put the levels
into context.
� Detailed discussions with staff were carried out to identify realistic ways of modifying
behaviour.
Using a dosimeter, noise levels measurements were made in an infant’s cot both before and after the
education programme. The study found an average decrease of 8 dB LAeq following the programme.
Kahn et al (1999) conducted a two part study which sought to limit noise in the ICU of a Rhode Island
hospital by behaviour modification. Firstly, twelve of the loudest sources of noise were identified. It
was found that half of these sources were attributable to human behaviour and thus could be
potentially modified (with talking and the television as the most prominent). A staff training programme
was devised and implemented, following which a behaviour modification programme was enforced for
a three week period. The study found that the programme was effective in reducing the noise levels
and recommended that it be used as one part of a larger noise control programme.
A study conducted by Johnson and Thornhill (2006) came to the same conclusions as Kahn et al, but
stressed the need for support from management in any attempt at long term behaviour modification. A
team effort in noise reduction was required for success.
3.4.1. Discussion
Studies have shown that as part of a training programme staff initially make efforts to modify their
behaviour, especially if the training period is being monitored. However, after this initial period it is
potentially difficult to motivate staff to continue.
Staff must be enthusiastic for behavioural modification programmes to work. These programmes need
frequent re-evaluation, education and feedback to reinforce behavioural change. This is only possible
with 100% support throughout the entire staff hierarchy. Management must realise the benefits of
noise reduction, otherwise this is not a realistic proposition.
For a culture of quiet to be re-adopted within hospitals, a complete change of attitude is required. This
is not only necessary from a staff and management perspective, but also required of visitors who need
to be aware and respectful of the needs of the other patients around them.
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3.5. The effects of room acoustic design modifications
Good room acoustic design essentially means that the acoustics are adapted to the activities being
carried out in the space. In theory, hospital room acoustics should not only aim to reduce the sound
level, but give priority to both speech clarity (as clear communication between staff, and staff and
patients is paramount), and speech privacy for patients.
Hospitals rooms are generally made up of hard, easy to clean surfaces. Carpets and curtains are
rarely used. As mentioned in Section 2.2.1 a suspended ceiling is generally the only feasible area that
can be used for the placement of sound absorbing materials. Ceilings provide a relatively large area
for sound absorbency and this can have the following effects: (i) reduction in the room reverberation
time; (ii) reduction in the measured sound level of the room; (iii) improvement in speech intelligibility.
This section reviews studies where physical changes have been made to room acoustics and the
subjective and physiological impact of patients examined.
3.5.1. Control of Infection and room acoustics
As discussed in Section 2.5, there has recently been a great deal of concern regarding the use of
acoustically absorbent materials in areas where Control of Infection is important. The study described
below by McLeod et al (2007), demonstrates one method of introducing effective, long term noise
reduction, whilst meeting healthcare standards and minimising costs.
The study was carried out in an immuno-suppressed Haematological Cancer ward of the Johns
Hopkins Hospital, Baltimore, US, which had been built with a reflective, solid ceiling after concerns that
the small holes typically found in an acoustic ceiling might harbour bacteria. The chosen approach was
to add custom-made sound absorbing panels to the walls of the unit. These were made by the
research team and consisted of glass fibre wrapped in anti-bacterial fabric, as at the time only a single
vendor was found to be selling suitable material; a review of manufacturers’ literature shows that this
has since improved. Objective and subjective data were collected before and after the installation of
the sound absorbers. It was found that there was an approximate drop of 5 dB in the measured LAeq
and the reverberation time was more than halved. The subjective view was that the unit had changed
from one perceived to be 'very noisy' to one that was 'relatively quiet'
Based on anecdotal evidence, it was concluded that the immediate impact of the sound absorbing
panels was to permit patients, staff, and visitors to lower the level of their voices whilst still being well
understood. It was felt that this probably accounted for the majority of the sound level drop. Staff
commented on how loud the telephone and overhead paging system sounded after installation of the
panels, and subsequent steps were then taken to lower the volume of these systems. The drop in
sound level was also felt to promote a safer environment with greater confidence in understanding
speech.
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3.5.2. Physiological response to acoustic modification
The physiological response of neonatal babies was examined by Johnson (2001). Previous studies
had found higher sound levels inside an incubator than in the open neonatal intensive care unit. It was
thought the primary causes were the incubator operating motor and care giving equipment, such as
the ventilator and suction tubing. Acoustic foam was added to an incubator and found to significantly
reduce environmental noise. The response of the neonatal babies to this noise reduction was
measured as changes in oxygen saturation. It was found that there was a significant correlation
between environmental noise and levels of oxygen support therapy required by the neonates.
A study by Hagerman et al (2005), examined the role of room acoustics on patients with coronary
artery disease admitted to the Huddinge University Hospital, Sweden. The study focussed on changes
of physiological parameters which were previously shown to be sensitive to physiological arousal.
These parameters were heart rate, heart rate variability, blood pressure (systolic and diastolic), and
pulse amplitude. A subjective response from patients was also analysed; this took the form of a
questionnaire with a number of questions about the quality of care.
The study took place over a period of eight weeks. During the first four weeks the ceiling tiles in the
patient rooms and the main work area consisted of sound reflecting plaster tiles (‘bad’ acoustics). For
the last four weeks these ceiling tiles were changed to Class A sound absorbing tiles (‘good’
acoustics). The tiles were visually identical. A total of 94 patients were analysed during the eight week
study period. It should be noted that the average stay within the unit was 17 hours, so no patients
were present during both ‘bad’ and ‘good’ acoustic periods.
Impacts of the changes were:
� During the 'good’ acoustics period sound pressure levels fell marginally, but the reverberation
times were halved. Speech intelligibility (as measured by the RASTI method and by subjective
reports from staff) was found to improve considerably.
� There was found to be a significant difference in pulse amplitude at night between groups
during the ‘bad’ and ‘good’ acoustics periods, together with a significantly greater need for
extra intravenous beta-blockers for patients (suggested to be an indication of pain) with ‘bad’
acoustics.
� Patients treated during the ‘good’ acoustics period considered staff attitude to be much better
than those treated during the ‘bad’ acoustics period.
� There was a higher incidence of re-hospitalisation at both 1 and 3 months in the group with
‘bad’ acoustics compared to the ‘good’ acoustics group. Early mortality was not found to differ.
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3.5.3. Discussion
The study carried out by McLeod et al (2007), showed an innovative way of making sound absorbers
which met Control of Infection standards. As discussed earlier in Chapter 2, it seems that no clear
design guidelines are readily available regarding the choice of acoustic materials for use in areas
where there are concerns about infection control. The review by the authors suggests that this is not
just an issue in the UK, although the study indicated that improvements are being made regarding the
choice of products available, and this had been found to be the case from a recent review of
manufacturers’ literature.
The improvement in the acoustic design of a space (by the addition of sound absorbing materials) has
been shown to improve both objective measurements and subjective perceptions. Speech intelligibility
is also enhanced, resulting in the lowering of voices and hence a quieter noise climate.
Only a single study was found which attempted to link the change of acoustic design with a lowering of
re-hospitalization rates. It is felt that with a sample set of patients suffering from complex and serious
conditions, there are too many variables involved to draw any meaningful conclusions in this regard.
There appear to be few studies which systematically vary acoustic conditions. This is an area which
could usefully be investigated further, however in practice this would be difficult to achieve in a working
hospital environment.
3.6. Conclusions
This chapter has reviewed studies which have objectively measured sound levels in hospitals, and
examined the effects of changing the room acoustics on both noise levels and on the physiological
responses of patients and staff. Many of the results and the limitations of the previous studies have
been used to inform the design of the current study, which is discussed in Chapter 5. The following
chapter discusses previous research which has investigated the effects of noise on staff and patients.
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4. The effects of noise on staff and patients
4.1. Introduction
This chapter focuses on previous research which looked at the effects of noise on staff and patients in
healthcare environments. For the purposes of clarity this review is divided into two categories: (i) the
effects of noise on healthcare staff and (ii) the effects of noise on patients. Discussion regarding study
findings, design limitations and areas which appear to be lacking in research is provided at the end of
each section. It should be noted that in some areas very few studies have been undertaken and these
few are regularly cited in the research literature. This is especially true of studies investigating the
effects of noise on patients.
4.2. Effects of noise on staff
4.2.1. Stress levels and burnout
Topf and Dillon (1988) investigated whether noise-induced stress was a predictor of burnout in critical
care nurses. Two university hospitals on the west coast of America were involved in the study, with
100 critical care staff from a range of backgrounds surveyed. The surveys were designed to build up a
picture of the stress that the healthcare staff felt they were under, and were not only related to noise,
but assessed other factors including stress caused by life events and occupational stress.
The results supported the hypothesis that a greater degree of noise would be linked with a greater
degree of burnout. The study also found that nurses with an intrinsic sensitivity to noise were no more
at risk from burnout linked with noise induced stress than those intrinsically less sensitive.
As part of the study staff were asked to indicate which noises were felt to be the most disturbing.
These were compared to those found in a previous study by the authors examining patients after
surgery. Staff cited beeping monitors, equipment alarms and telephones as the most disturbing
sources; patients cited loud talking in the corridor at night and other patients coughing and snoring.
The study raised the interesting point that the noises most disturbing to nurses may be perceived by
patients as necessary for recovery.
4.2.2. Cognitive function / memory
The studies in the following paragraphs attempt to show the effects of hospital noise on cognitive
function and short-term memory of staff, by simulating surgical environments. The findings are
contradictory; hence it is thought that a simulation of this type of environment in a laboratory is not
wholly representative of a hospital situation.
Murthy et al (1995) examined the effects of noise on cognitive function and short-term memory of a
group of twenty anaesthetists. Following a measurement period within an operating theatre, a 90
minute audio cassette was created to be representative of typical operating room noise. This was
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played to the anaesthetists who undertook a series of tests. The study concluded that exposure to the
recorded noise caused deterioration in mental efficiency and short-term memory in the subjects of the
study.
Moothy et al (2005) evaluated the effect of noise on the performance of a complex laparoscopic task.
Twelve surgeons undertook this task under three controlled laboratory conditions – quiet, noise at 80
to 85 dB and background music. A validated motion analysis system was used to assess
performance. The noise used was monotonous repetition of background operating theatre noise and
did not involve any sudden bursts of sound. It was found that neither the noise nor the music had any
significant effects on task performance. It was considered likely that surgeons had learnt to effectively
block out the presence of the auditory stimuli.
4.2.3. Effects of acoustic design on the work environment
The study by Hagerman et al (2005) cited in Section 3.5.2, not only examined the influence of
different acoustic conditions on patient physiology, but also on the work environment and the staff in a
Coronary Critical Care Unit. During the first four weeks the ceiling tiles in the patient rooms and the
main staff work area were sound reflecting plaster tiles (‘bad’ acoustics). For the last four weeks these
ceiling tiles were changed to Class A sound absorbing tiles (‘good’ acoustics). The tiles were visually
identical.
Thirty six regular members of staff were asked to participate in the investigation of the psychosocial
environment and emotional states, and were required to complete a questionnaire at the start and end
of each shift. The questionnaires were designed in line with the 'demand-control-support model',
frequently used in healthcare to analyse work related stress.
During the ‘good’ acoustics period it was found that staff (particularly on the afternoon shift)
experienced significantly lower work demands and reported less pressure and strain. Staff also
reported feeling more relaxed and less irritable, and considered speech intelligibility to have improved.
Caution must be taken in interpreting results of studies of this nature. Although objective
measurements showed a change in some acoustic parameters, there are many other contributing
factors such as work load and tiredness, which may have an effect on the staff mood and their
perceived stress levels. This study did not appear to take these other factors into consideration, and
as such the findings may be compromised.
4.2.4. Discussion
There appear to be very few studies which deal with the effects of the acoustic design on staff
outcomes such as job stress, work demands, fatigue, and quality of patient care.
Although it appears that each member of staff is individual in their tolerance to and their perception of
noise, one regularly cited area of disturbance is that of equipment noise.
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Interestingly, one study indicates that the noises most disturbing to nurses may be perceived by
patients as necessary for recovery.
Concerns are raised regarding staff speech communication without errors and the fatiguing effects of
having to communicate with a raised voice.
Some evidence exists that staff may be able to effectively tune out auditory stimuli whilst performing
tasks which require a high degree of concentration. However, laboratory studies examining the effects
of noise on surgical task performance proved to be contradictory.
4.3. Effects of noise on patients
4.3.1. Recovery rates
In an opportunistic study, Fife and Rappaport (1976) took advantage of construction work being
carried out outside the University of Minnesota hospital to examine the effects that this might have on
the recovery rates of patients. The building works were situated outside the rooms of patients
recovering from a cataract operation. Comparisons were made between discharge rates a year prior
to the study and discharge rates one year later. It was assumed that discharge dates were
determined by wound healing.
The study sample chosen were patients that were undergoing simple cataract surgery, who were free
of any diagnoses that were likely to cause complications. This made the results of the study less
subject to variation. It was found that the difference between the average length of stay during the
noisy period and the pooled quiet periods was statistically significant, increasing from 8.7 days to 9.9
days (p<0.05, one tail test).
4.3.2. Subjective response to noise
Allaouchiche (2002) undertook a multi-disciplinary study looking at the effects of noise on patients
recovering from the effects of anaesthesia. The study, carried out in the post anaesthesia care unit in
a hospital in Lyon, France, involved 26 adult patients. Objective measurements were taken with the
sound level meter positioned close to the patient’s head. Patients were interviewed two hours after
discharge and asked to complete two questionnaires to assess their experiences on the unit. The first
questionnaire was unstructured; the second was structured and asked questions about common
complaints, including noise.
The study concluded that high levels of noise were present and that the majority of this noise could
have been prevented. However, noise was not perceived by patients as the main cause of discomfort,
with only 19% (five patients) identifying noise as an important factor. Of these, four complained about
conversation and one about equipment alarms. It was shown that approximately 55% of sound peaks
greater than 65 dBA were caused by conversation.
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Pugh et al (2007) note an interesting point in their review of noise studies in ICUs. Each patient is
individual in their tolerance for, and how they view, noise. Some patients like the reassurance of
hearing alarms and having people talking around them because it makes them feel safe. The review
concluded that the impact of noise should be reduced by a three way approach - modifying staff
behaviour and practices, minimising the disruption caused by equipment and alarms and optimising
the acoustic design of the ICU.
4.3.3. Speech privacy
Barlas et al (2001) examined whether patients perceived less privacy in A&E curtained treatment
areas than in walled rooms and concluded that patients from curtained areas did report significantly
less auditory, visual and overall privacy than those in rooms.
The study made several points worthy of note:
� 85% of patients reported a high degree of respect for privacy from the staff.
� A small percentage of patients in the curtained areas withheld portions of their medical history
or refused part of their medical examination because of privacy concerns.
� Older patients believed that they could hear others' conversations with a physician or nurse
more often than younger patients.
� It was felt that due to the sensitive nature of some of the questions posed, responses may not
represent the true feelings of the individuals.
4.3.4. Single bed patient rooms
Van de Glind et al (2007) noted that an increasing number of hospitals have taken the decision to
provide single bed patient rooms. It is not clear if these policy decisions are based on scientific
evidence. The study reviewed the literature currently available on the benefits of single bed rooms,
and examined the following: privacy and dignity, patient satisfaction with care, noise and quality of
sleep, hospital infection rates, recovery rates and patient safety issues. The study concludes that due
to the lack of research, there is currently not enough evidence to prove that the introduction of single
bed rooms is beneficial.
4.3.5. Discussion
Only one single, opportunistic study was found which attempted to link patient recovery rates to noise
levels. Further research in the area would be beneficial, but the number of variables involved in
carrying out studies in healthcare makes meaningful results difficult to obtain.
Although it appears that each patient is individual in their tolerance for and how they view noise, one
regularly cited cause of patient disturbance is staff conversation. It was found that some patients like
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the reassurance of hearing alarms and having people talking around them because it makes them
feel safe.
Privacy concerns may cause patients to withhold portions of their medical history or refuse part of
their medical examination. This appears to be particularly relevant in the case of more elderly
patients.
4.4. Conclusions
This chapter has highlighted the lack of extensive research studies examining the effects of noise on
staff and patients, and the difficulty of obtaining reliable and meaningful data in both hospital
environment and simulated laboratory studies. This lack of data has influenced the current study
which aims to further investigate the subjective perceptions of staff and patients to noise in a range of
ward types. This is discussed further in the following chapter.
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5. Study design
5.1. Introduction
The aims and objectives of the current study were informed by the literature review, with input from
the industrial partner, Arup Global Healthcare. This chapter outlines the aims and objectives of the
research and discusses the objective and subjective survey methods used in more detail. The
preliminary work involved in obtaining ethical approval and the necessary permissions to carry out the
study within an occupied ward environment of a hospital are also discussed.
5.2. Study outline – aims and objectives
The following conclusions drawn from the literature review were seminal in informing the proposed
study design:
� Very few studies have been carried out in general inpatient hospital wards.
� The majority of previous studies have been undertaken by healthcare staff with little
knowledge of acoustics. This has led to inconsistencies in the use of acoustic parameters;
short or incomplete measurement periods; unknown microphone positioning and a general
lack of rigour.
� Few studies have compared noise levels in multi-bed and single bed patient accommodation;
nor have they attempted to build up an overall picture of the noise climate of a ward.
� There is a noticeable lack of studies carried out in UK hospitals.
� Only one study was found which investigated the relationship between acoustic design and
design for infection control purposes.
� Further studies exploring patients’ perceptions of privacy would be beneficial.
� The current UK acoustic design guidelines are effective in terms of general construction
advice, but have less relevance in terms of occupied ward areas.
The current study therefore aimed to address many of these issues, and this is discussed in the
following sections.
It was decided that the proposed research would be both objective and subjective in its nature. The
objective study would consist of an acoustic survey to obtain data on the noise levels and acoustic
conditions in inpatient hospital wards. The subjective component would aim to build up an
understanding of staff and patient perceptions of noise in the same ward environments by use of
questionnaire surveys.
It was felt that the hospitals involved in the study should be chosen to reflect a broad range of building
and ward designs, different types of inpatient care and a mixture of surgical and medical wards. This
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would allow many useful comparisons to be made. Buildings undergoing refurbishment were of
special interest for pre and post intervention studies.
Individuals working in healthcare estates with links to the Medical Architecture Research Unit at
London South Bank University were contacted to locate possible study sites. Three potential sites
were identified: Great Ormond Street Children’s Hospital, London; Bedford Hospital, Bedford; and
Addenbrooke’s Hospital, Cambridge.
5.2.1. Acoustic survey
The main aim of the acoustic survey was to build up a picture of the noise climate within general
inpatient care wards by making a comprehensive series of noise measurements. The data captured
would include average, maximum and background noise levels and the identification of the sources of
high level noise. Noise levels during the day and night would be investigated to allow for comparison
with relevant standards.
Particular consideration would be given to building construction, ward layout, the amount of acoustic
absorbency provided and how the design for control of infection affected the acoustic comfort within
the space. Where possible, factors such as ceiling finishes, ventilation systems and glazing were also
to be investigated:
It was thought that the use of technology on the ward might have a negative impact on the noise
climate. Staff systems, medical equipment and patient entertainment (including TV and radio) were
therefore investigated to build up an understanding of the effects of their use on the noise climate.
In addition to noise measurements other room acoustic parameters such as reverberation times were
considered to provide further indication of the acoustic comfort of the space.
It was felt that the data captured during these objective studies would be invaluable in understanding
the key elements of the noise climate in inpatient care and link directly into the following areas:
� understanding of the physical and behavioural factors that significantly affect the noise
climate
� the effects of acoustic design changes on the acoustic comfort of a space
� exploration of the conflicts between design for infection control and acoustic comfort
5.2.2. Questionnaire surveys
Initially it was hoped that a subjective assessment of the noise climate in inpatient care could be
undertaken using a semi-structured interview approach, talking to both staff and patients. However it
became apparent that to obtain ethical approval within the project time constraints, a questionnaire
survey approach would be more suitable. Further details concerning the need for ethical approval can
be found in Section 5.5.
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Two questionnaires were designed, one for the ward medical staff and another for patients whose
stay on the ward was longer than 24 hours. The aim of the questionnaires was to build up an
understanding of the perceptions of both staff and patients regarding noise in their environment, and
ultimately to establish whether any relationships existed between the objective data collected on the
wards and the perceptions of the ward users.
Good questionnaire design is paramount if meaningful data is to be collected in a survey of this type.
The use of leading words or questions should always be avoided. As such, a great deal of thought
was given to the type of information that was required, and many questions were discarded before
reaching the final versions.
The length of time taken to complete the questionnaire was also considered. Staff are very busy and
unlikely to complete a survey which may take longer than five minutes. Patients, also, would find a
long questionnaire daunting, especially if they were feeling unwell or weak. With this in mind the
questionnaire was kept relatively short and the layout was designed for clarity and ease of
completion.
Questionnaires in their final form were trialled throughout the pilot study (see Chapter 6). Responses
were reviewed and any questions that were felt to be ambiguous were rewritten.
Further details on the design of the questionnaire surveys can be found in section 5.4 of this chapter,
and sample questionnaires can be viewed in Appendix A.
5.2.3. Comparison studies
The ultimate aim of the study was to make use of the objective and subjective data captured in the
following ways:
� comparison studies of single and multi-bed inpatient accommodation
� comparison studies of inpatient wards situated in buildings of differing age, construction and
layout
� a comparison study of a surgical and medical inpatient ward
� examination of the perceptions of the acoustic environment of patients and staff
� identification of the dominant; most annoying; and most disturbing noise sources
� analysis of noise, acoustic and subjective data in order to suggest methods of noise control,
particularly in the areas of equipment and human interface
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5.3. Acoustic survey methodology
5.3.1. Equipment
The following equipment was used throughout the study:
� Norsonic 140 Class 1 Sound Level Meter
� Norsonic Sound Calibrator Type 1251 (114 dB @ 1000Hz)
� Norsonic Environmental Case with two additional heavy duty batteries
� Additional heavy duty batteries to allow for quick equipment rotation
� 5 m microphone extension cable
� Mini microphone tripod / 300 mm ceiling bracket
To allow for longer term measurements to be made, the sound level meter (SLM) was placed in an
environmental case with two heavy duty batteries. The life of the batteries was such that one week’s
worth of data could be collected at each measurement position before replacements were required. A
five metre extension cable allowed the microphone to be placed away from the environmental case,
which afforded flexibility regarding its positioning, see Figure 5.1.
Figure 5.1 Sound level meter, environmental case and associated equipment
5.3.2. Control of Infection
Due consideration was given regarding the choice of equipment and whether it could be easily wiped
clean if necessary. It was felt that the environmental case, which was made of tough plastic, was
easily cleanable. However the microphone, being extremely sensitive, would not be cleanable to any
degree. It was therefore decided that if the microphone was positioned out of reach, it was unlikely to
be touched and contaminated, and thus unlikely to need specific cleaning for purposes of infection
control. Meetings with a member of the hospital Control of Infection team were held at each study site
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to ensure that the use of the noise measurement equipment was acceptable and met with hospital
infection control policies.
5.3.3. Acoustic parameters
To allow an acoustically robust picture of the noise climate to be built up, the following parameters
were measured: LAeq,1hr, LAmax, LA90, LAmin and LZ(SPL) and reported where appropriate.. The third octave
frequency band spectrum of the sound was also included. Throughout the study the SLM was set on
a fast time weighting.
At each change of measurement location the data captured was downloaded onto a laptop computer
and reviewed further using the software provided by Norsonic, the manufacturer of the SLM. This
software, ‘NorReview’, allowed all captured data to be viewed graphically; to be analysed in detail;
and subsequently exported into a Microsoft Excel spreadsheet for reporting purposes.
5.3.4. Presentation of sound levels
To build up an understanding of the noise climate in each ward location, sound levels are presented
throughout the study in a number of different ways:
The measured LAeq,24hr, LAeq,16hr and LAeq,8hr quoted in tables for each ward are arithmetic averages of
each metric over the number of days in the measurement interval. For example, if five days worth of
data have been collected, the reported LAeq,16hr is the arithmetic average of the five daily measured
LAeq,16hrs.
Where average LAeq,1hr and LA90,1hr levels are shown graphically over 24 hours, this is again the
arithmetic average of each metric over the measurement period. For example, for a five day
measurement period, for the time interval 11.00 to 12.00, the LAeq,1hr would be the arithmetic average
of five LAeq,1hrs measured from 11.00 to 12.00.
Any other sound level presented is defined and labelled.
5.3.5. Measurement interval
Many of the measurement intervals in the reviewed studies were either short (less than 24 hour) or
incomplete. It was felt that to build up an accurate picture of noise in inpatient care it was extremely
important to establish a representative measurement interval. This interval could then be used
throughout the main study. This is discussed further in Section 6.14.
5.3.6. Measurement locations
To fully understand the noise climate of a ward, measurements were undertaken in each type of
patient accommodation and at the nurse stations. For example, if a ward consisted of four bed and
single room accommodation, it was decided that at least two single rooms and two 4-bed bays should
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be measured. This would ensure that the data captured was typical of the accommodation type and
enable comparisons to be made.
5.3.7. Identifying sources of high level noise without an observer
Previous studies conducted in healthcare environments often made use of a team of observers to
note down the sources of high level noise. Identifying these sources is important, as it allows some
noise control or other remedial measures to be put in place to counteract unnecessary noise. Of
course the use of observers is only possible in the short-term. Where longer measurement periods
are proposed, this is not realistic or practical.
The SLM used in the study incorporated built in ‘level above’ trigger functionality. By enabling this
feature, a short sound file is created as soon as the value of LAmax exceeds a specified threshold.
Once the data is downloaded for analysis, each sound file can be reviewed and the sources of the
high level noise identified.
5.3.8. Reverberation times
Reverberation time (RT) is generally used as an indicator of the acoustic comfort of a space and is an
important measurement in the field of room acoustics. There are a number of methods used to
measure the RT value. The two widely used methods listed in the British Standard BS EN ISO 3382:2
(2008) are the Interrupted Noise Method or the Impulse Response Method. Both methods rely on
generating high level noise, which would generally be unacceptable in an occupied hospital ward.
It was decided that if an opportunity arose to make RT measurements in unoccupied patient
accommodation, then the Impulse Response Method should be used with a balloon burst as the
source. This was purely down to the logistics of carrying bulky equipment into a hospital.
Loudspeakers and amplifiers would be required if the Interrupted Noise Method was chosen, and this
was not practical.
Where the Impulse Response Method was used, the number of source and receiver positions
stipulated by British Standard BS EN ISO 3382-2 (1998) for ‘engineering’ work was adhered to with
RT20 values for octave frequency bands from 250 Hz to 4000 Hz reported. For this category at least
two source and at least two receiver positions were stipulated for each measurement.
Where on site RT measurement was not possible, an estimation method was used which made use of
‘level above’ trigger sound files. This is discussed in further detail in Chapter 10.
5.4. Questionnaire survey design
This section describes the design of the staff and patient questionnaires used in the study. Examples
of each questionnaire can be seen in Appendix A.
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5.4.1. Staff questionnaires
The first section entitled ‘About You’ was designed to categorise certain staff attributes by identifying
sex, age bracket, staff grade, length of service on the ward and at the hospital. The questions were
very general, without asking anything that could be deemed as too personal or intrusive. It was
thought that with a large overall dataset, these categories may help to establish relationships
between, for example, the length of service and noise annoyance.
The second section entitled ‘About Your Environment’ examined perceptions of noise annoyance and
noise interference with the ability to work. It was felt that it was important to not only examine noise
annoyance but also whether staff felt that their work was impacted by certain sounds. The
questionnaire sought to identify the sources of both annoyance and interference by providing a list of
noises (which were identified from initial observations made in the pilot study ward). Staff were asked
to rate the annoyance / interference of each noise source listed on a scale of 0 to 4 (where 0 indicated
no annoyance / interference and 4 indicated a great deal). Several lines were left blank at the bottom
of the lists for staff to add and rate additional noise sources.
The third section aimed to aid understanding of which sounds were felt by staff to be important in
order to carry out their jobs effectively. Staff were asked to rate the sounds on a scale of 0 to 4, where
0 indicated ‘not at all important’ and 4 indicated ‘extremely important’. Again, several lines were left
blank at the bottom of the lists for staff to add and rate additional sounds that they considered
important.
A comments section was left at the end of the questionnaire for any additional feedback.
5.4.2. Patient questionnaires
The first section entitled ‘About You’ was designed to categorise certain general attributes by
identifying sex, age bracket, length of stay on the ward and bed number. As with the staff
questionnaires the questions were very general, without asking anything that could be deemed as too
personal or intrusive. The following provides the reasoning behind this line of questioning:
� The sex of a patient may yield information regarding differences between men and women
regarding sensitivity to noise.
� The age group of the patient may be related to their sensitivity to noise, as hearing generally
deteriorates with age.
� How long a patient has been on the ward may indicate whether there is a correlation between
length of stay and becoming more acutely aware of noise, or whether an individual becomes
more used to the noise levels.
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� The patient’s bed number provides location information. Relationships may be shown to exist
between bed location and specific sources of noise.
The second section titled ‘About Your Environment’ considered noise annoyance both during the day
and at night. The questionnaire sought to identify the sources of noise that may annoy or disturb
patients. Respondents were given a list of noises (which were identified from initial observations
made in the pilot study ward), and were asked to rate the annoyance / disturbance on a scale of 0 to 4
(where 0 indicated no annoyance / disturbance and 4 indicated a great deal). Several lines were left
blank at the bottom of the lists for patients to add and rate additional noise sources.
The third section of the questionnaire contained a number of questions designed to investigate the
acoustic environment further, including perceptions of speech privacy. The following paragraphs
discuss the contents of this section further:
Sound was examined in a positive rather than in a negative light, with patients asked if there were any
sounds that they actually found comforting. Three blank lines were provided for a response.
Communication between nursing staff and patients was investigated, by asking patients whether they
could clearly hear what was said to them by the medical staff. The aim of this question was to
highlight high levels of background noise and poor acoustics, but of course a patient suffering from a
hearing impairment would have difficulty hearing for other reasons. To take this into consideration,
patients were also asked if they had a hearing impairment. It was felt that asking details of the
impairment would be deemed too personal, and so a ‘yes’ or ‘no’ response to this question was
provided.
Conversational privacy was investigated by asking whether a patient felt that they could have a
private conversation at their bedside. If the response was in the affirmative, a further question was
asked to see if the patient would feel comfortable speaking normally or whether they would need to
lower their voice or take some other precautionary measure.
Finally, respondents were asked if they felt that there was ever too little sound in a room. This
question was asked as some previous study findings suggest that patients may feel isolated if it is too
quiet.
A comments section was left at the end of the questionnaire for any additional feedback.
5.5. Preliminary work
5.5.1. Building relationships with hospitals and Healthcare Trusts
Following the agreement of the project proposal, meetings were held with estates staff at each of the
proposed locations. It was considered very important that the estates teams supporting the study felt
that it would provide them with useful data. Study feedback could potentially provide information on
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the current performance of the occupied buildings on site, and could be used to inform the design of
future site developments or refurbishments.
Feedback from the initial meetings was positive, and further meetings were held with the members of
the estates teams and senior clinicians to ascertain the best inpatient ward locations in which to
conduct the study at each site.
It was agreed that a pilot study would initially take place at Great Ormond Street Children’s Hospital. It
was felt that the study could yield useful information for the hospital’s redevelopment team about the
acoustics of the Octav Botnar Wing, whose design was heavily influenced by the need for infection
control, with hard, easily cleanable surfaces.
5.5.2. Ethics and Trust approval
Before any part of the study could be started, the necessary permissions needed to be granted by
each Trust. These permissions involved a personal police check of the researcher who would be
working at each site, and a statement of ethical approval from both the central NHS Ethics Service
and London South Bank University.
National Research Ethics Service
All proposed healthcare studies require a level of scrutiny by the National Research Ethics Service
(NRES). The advice published by the service is biased towards clinical trials and is hard to interpret.
Some short-term projects have failed entirely due to the length of time involved in granting ethical
approval.
After consulting with NRES, it became apparent that there would be no ethical issues surrounding the
proposed objective study, which would be viewed as an ‘audit’. However, ethical approval would be
required if staff and patients were to be interviewed. This would mean a very lengthy process waiting
for committee decisions.
Further discussion with NRES suggested that if, rather than interviewing staff and patients, an
anonymous questionnaire was used, submission to an ethics committee might not be required, with
the study being classed as ‘a service evaluation’.
A document was prepared explaining the planned use of staff and patient questionnaires. This
document along with details of the objective study, a poster advertising the study, staff and patient
information sheets and copies of the questionnaires were all submitted electronically to NRES. The
response classed the study as a ‘service evaluation’ and confirmed that a Research Ethics Committee
review was not required.
Copies of all documents mentioned above can be found in Appendix A.
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London South Bank University Ethical Review
Following the response from NRES, an application for ethical review was submitted to the Executive
Dean of the Faculty of Engineering, Science and the Built Environment at London South Bank
University.
The London South Bank University Code of Practice for Investigations on Human Participants deems
that ‘Class 1 Investigations are any investigation taking the form of a general survey / questionnaire /
interview (including telephone surveys) which do not involve the request or receipt of personal
information, as defined by the Data Protection Act 1998, from the participant’. The Code of Practice
states that Executive Deans may approve Class 1 Investigations providing these comply with this
Code of Practice.
It was felt that this study fell into the category of a Class 1 Investigation and as such the relevant
documentation was sent directly to the Executive Dean for review. Ethical approval from the
University was given forthwith and evidence is provided in Appendix A.
Hospital specific permissions
Once ethical approval had been received from NRES and London South Bank University and the
police checks had been finalised, temporary contracts of employment and security passes could be
issued by each Trust. The onsite study was then able to commence.
5.6. Conclusions
This chapter has described the design of the objective and subjective surveys, plus the preliminary
procedures that were necessary in order to carry out research in occupied hospitals. The following
chapter describes the pilot study that was undertaken to validate and further develop the methods
discussed in this chapter.
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6. Pilot Study
6.1. Introduction
A pilot study involving acoustic and questionnaire surveys was carried out in a post surgical inpatient
ward in a five year old building at Great Ormond Street Children’s Hospital, London. The aim of the
pilot study, which took place over a four month period from September to December 2009, was
twofold: to test the methodology to be used in the main study to ensure that meaningful results could
be obtained in line with the research proposal; and secondly, to provide useful feedback for the
redevelopment team and the ward manager on site. The design of this particular building was heavily
influenced by the need for infection control, with hard, easily cleanable surfaces. The redevelopment
team were interested to find out how the building performed acoustically post occupation, and
whether the design compromised this performance in any way.
Particular consideration was given to the following aspects of methodology to identify the optimal
dataset to be collected in the study and to ensure it would be as robust and reliable as possible.
� The choice of suitable microphone positions to allow for meaningful comparisons to be made
between patient accommodation types.
� Use of the ‘level above’ trigger functionality built into the sound level meter as a means of
identifying sources of high level noise.
� The choice of a representative measurement time interval.
� To check for ambiguous or misleading questions in the staff and patient questionnaires.
This chapter begins by looking at the background of Great Ormond Street Hospital for Children,
providing an overview of the acoustic design considerations of the study ward and exploring the
hospital policies and equipment usage that may affect noise levels. The chapter continues by
considering the most effective ways of positioning the measurement equipment and also ensuring
adequate publicity of the study. Objective results from each ward are reported, and staff and patient
perceptions of the noise environment are explored. The results of the study were reported back to the
ward staff in several meetings; their observations on the findings and possible actions are discussed
at the end of this chapter.
6.2. Background
Great Ormond Street Hospital for Children (GOSH) was established in 1852, and was first located at
49 Great Ormond Street, London. With its motto “the child first and always”, the hospital has become
the leading UK tertiary paediatric hospital, providing the widest range of specialist paediatric services
in the country.
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As part of an ongoing redevelopment plan for the site focusing on the delivery of a new model of care,
the construction of The Octav Botnar Wing was completed in early 2006, and is shown in Figures 6.1
and 6.2. This building was designed to provide a unique, uplifting environment for both patients and
staff by maximising the use of natural light, bright colours, and innovative designs. The Octav Botnar
Wing houses a number of specialist centres including an International Patient Centre; Medical Day
Care Centre; Orthopaedic Ward and Biomedical Engineering Centre.
Figure 6.1 Figure 6.2
The Octav Botnar Wing Main entrance to the Octav Botnar Wing
6.3. Sky Ward
Out of the four specialist centres situated in the Octav Botnar Wing, only the orthopaedic ward (known
as Sky Ward) fitted the research project criterion of general inpatient care. Length of stay here is
generally from one day to two weeks, with patients undergoing a number of different types of surgery
including limb lengthening procedures, and spinal, hip and foot surgery. Patient ages vary from
infancy up to 18 years of age.
The new clinical facilities were designed to provide greater space for patients, more comfortable
surroundings for a parent to stay by their child’s bedside and more efficient use of space for nursing
teams. The ward is built on a "racetrack design" that positions patient rooms on the outer part of each
floor and locates the health care resources in the centre of the building. Consisting of three 4-bed
bays and six single patient rooms, there are a total of 18 patient beds. Rooms facing east and south
include floor to ceiling glazing looking out onto a balcony area (which is locked and not available for
use). Rooms facing west have smaller areas of glazing. All 4-bed bays and single rooms have ensuite
shower and toilet facilities. Each patient bed also has its own flat screen television, hoist, and a bed
for parents to sleep next to the patient (the single rooms have a pull down bed; the 4-bed bays have
chairs which convert to beds). Figure 6.3 shows the brightly coloured ward reception area, and Figure
6.4 shows a patient bed in a 4-bed bay.
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Figure 6.3 Sky Ward reception Figure 6.4 Typical four bed bay
Healthcare resources are situated in the centre of the ward and include a clean and dirty utility room;
a plaster room; a sensory room; kitchen; assisted bathroom; equipment store; adolescent room; ward
manager’s office; and two nurse stations. A plan of the ward is shown in Figure 6.6 on page 51.
6.4. Building acoustic design considerations
The Octav Botnar Wing was built to conform to the Health Technical Memorandum HTM 2045:
Acoustics Design Considerations (NHS Estates, 1996), which contained partition performance
requirements as well as advice on many other aspects of acoustic design (as discussed in Chapter 2).
It was therefore assumed that floors, walls, windows and doors were of a reasonable specification in
terms of sound insulation and sound attenuation.
6.4.1. Nurse stations and common areas
Within the corridors and around the nurse stations there was no visible acoustic absorbency. The
ceilings at the nurse stations were solid plaster with round inspection hatches to access services. The
corridor ceilings were also solid plaster with a strip of metal ceiling tiles running down the centre to
provide access to services. Floors were heavy duty vinyl and walls were plasterboard on a metal grid
system.
6.4.2. Patient accommodation
The 4-bed bays and single patient rooms all had suspended ceiling grids with Armstrong Ultima
ceiling tiles. The properties of these tiles are shown in terms of their sound absorption coefficients (α)
at different frequencies in Figure 6.5.
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Figure 6.5 Ultima ceiling tile sound absorption coefficients (α) over a range of frequencies
Source Manufacturer’s datasheet
All patient accommodation has vinyl flooring and plasterboard walls mounted on a metal grid system.
Additional acoustic absorbency is provided by window curtaining, upholstered upright chairs, patient
and parent beds and privacy curtaining that can be pulled around each bed (4-bed bays only). Full
length curtains are also provided to pull around the parent bed in the single patient rooms for
additional privacy.
6.5. Ward routines
The ward manager of Sky Ward was enthusiastic and supportive of the study. He had some concerns
about several of the systems in place on the ward which he considered to be excessively loud. It was
decided that an investigation of these systems could be easily incorporated into the study.
To help inform the study design, some time was spent on the ward to build up an appreciation of ward
layout, to meet the staff and to make on-the-spot sound level measurements. Several discussions
with the ward manager helped to build up an understanding of the day-to-day running of the ward and
any events that could potentially affect the noise levels. This initial discussion process was found to
be useful and was used throughout the main study.
Information and events which were thought be of some significance are discussed in the following
sections.
6.5.1. Staffing and patient levels
Due to the nature of care in this particular ward, and the timings of the operations, staffing levels and
ward occupancy are generally at their highest during weekdays. Weekday staffing levels generally
consist of between three and five clinically trained staff, up to three students and up to two health care
assistants for a day shift, with fewer staff at night.
During a weekend, ward occupancy rates drop to less than 50%, staffing levels are lower and often
one 4-bed bay and several single rooms are left empty.
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Due to this drop in occupancy, it was decided that measurements made during the weekends would
not be representative of the typical use of the ward and it was therefore decided that analysis would
only be carried out on weekday measurements for the pilot study.
6.5.2. Staff shift patterns and ward rounds
Staff day shifts start at 07.45 and end at 20.15, with night shifts starting at 19.45 and ending at 08.15.
There is a 30 minute shift overlap between 07.45 and 08.15 and 19.45 and 20.15 with potentially
more staff gathered at the nurse stations for handover sessions. Higher levels of noise may be
attributed to these changeover periods.
Ward rounds generally start around 08.15 (after the completion of the shift handover), with many of
the children on the ward requiring hourly checks by medical staff.
6.5.3. Cleaning
Cleaning usually begins at 08.00. Daily cleaning generally consists of a felt floor mop to remove dust
(floors are buffed once every two weeks); the emptying of the two rubbish bins in each of the bays
and single rooms twice daily (general and chemical waste); the cleaning of the ensuite bathrooms;
and bed changing.
6.5.4. Meal times
Meal times are at 12.00 and 17.00 and last approximately one hour. Meals are individually served to
patients, with no meal round with a trolley. It was felt that it was unlikely that noise levels would be
impacted greatly by the serving of meals to patients.
6.5.5. Medical equipment with alarms
Three types of medical equipment are used on the ward which may contribute to noise levels:
� The fluid pump. This has a high pitched alarm if intervention is required.
� Heart rate and oxygen level monitor. This has a lower pitched ‘bong’ alarm if intervention is
required.
� A nebuliser which creates a mist of medicine which is breathed in through a mask or
mouthpiece. This is commonly used to give high doses of reliever medicine and when in
use makes a low level ‘bubbling’ sound.
6.5.6. Access to patient accommodation
All doors to the 4-bed bays are left open both day and night for staff observation. This is how the staff
at this hospital are trained to care for patients in multi-bed accommodation. If doors to a bay are shut,
it is assumed that there are no patients present.
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The doors of the single patient rooms are generally left open during the day (depending on the
patient’s preference and condition), but closed at night if there is a relative staying with the patient.
Patients given single room accommodation are generally infants under one year old, those with
special medical needs or infectious patients. Staff are happy for the doors to single rooms to be
closed if a patient is infectious or if the parent is with the child and can call for help if the need arises.
6.6. Measurement locations
It was considered important that the measurement locations chosen were those that could be easily
repeated within the main study and that the locations reflected the study aim: to build up a
comprehensive picture of noise levels in inpatient care. Figure 6.6 shows the ward layout which is
discussed further in the following sections.
6.6.1. Nurse stations
There were two nurse stations on the ward and these were located at either end of the central
healthcare resource block. It was felt that for comparison purposes it was important to measure noise
levels at both.
Nurse station 1 was closest to the ward entrance at the junction of several corridors. One corridor
provided access to the ward manager’s office and ward reception, with the other corridor running
down the length of the ward. A 4-bed bay was located opposite this nurse station. As the doors to this
bay were always left open, patients could potentially be affected by noise from the nurse station.
Figure 6.7 shows the nurse station, and Figure 6.8 shows the corridor running to the ward manager’s
office and ward reception.
Figure 6.7 Nurse station 1 Figure 6.8 Internal corridor
Microphone Position
Single Patient Room A
Nurses’ Station 2
Single Patient Room B 4 Bed Bay B
4 Bed Bay A
Nurses’ Station 1
Ward Entrance
Reception Desk
Waiting Area
Figure 6.6 Layout of Sky Ward with microphone positions
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The nurse station was a semicircular desk with a number of drawers, on which a computer,
printer, telephone, security monitor and the nurse call control panel were installed, as shown
in Figure 6.9. There was a small grill on the wall behind the desk covering the loud speaker
to which the nurse call system and doorbell were piped. This loud speaker can be seen
labelled in Figure 6.10.
Figure 6.9 Internal telephone & security monitor Figure 6.10 Wall mounted speaker grill
Nurse station 2 was much larger than its counterpart and tended to be busier, with more staff.
It was located at the opposite end of the ward to nurse station 1, with two single patient rooms
directly opposite and a 4-bed bay to the right. Due to the open door observation policy the 4-
bed bay could be potentially affected by noise from the nurse station. To either side of the
nurse station were sets of double doors but these were left open at all times, except in the
event of fire, when they would automatically be closed.
As with nurse station 1, this location was a semicircular desk with a number of drawers, on
which several computers, a printer, a telephone, security monitor and the nurse call control
panel were installed. This can be clearly seen in Figures 6.11 and 6.12. Again there was a
small grill on the wall behind the desk covering the loud speaker to which the nurse call
system and doorbell were piped. Patient notes were kept in ring binders and there were often
a number of ring binders laid out on the top of the desk.
Speaker grill
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Figure 6.11 Nurse station 2 Figure 6.12 Nurse station 2 desk
6.6.2. Four bed bays
Two different 4-bed bays were chosen for comparison purposes. The rooms were different
shapes, had different bed positioning and differing amounts of glazing. Identical facilities were
available for patients.
4-bed bay A faced out onto nurse station 2 and was accessed through a set of open double
doors. To the left hand side of the ward entrance was a hand washing sink and two rubbish
bins for chemical and general waste. There were two beds positioned on the left hand side of
the room and two on the right. Each patient bed could be ‘curtained off’ from the ward, which
was often the case when the bed was occupied, presumably for reasons of privacy. Parents
were provided with a chair which converted to a bed so that they could sleep next to their
child at night. At the back of the bay were floor to ceiling windows and a glazed door opening
out onto the balcony area. The windows and door did not open; this bay was mechanically
ventilated only. In the back right hand corner a set of metal lockers were provided for parents
to store valuables, next to which was the door to the ensuite shower room.
4-bed bay B (shown in Figure 6.13) was situated at the opposite end of Sky Ward facing the
smaller of the two nurse stations. Unlike bay A, this bay was ‘L’ shaped, with two beds
situated on the right hand side of the room and two beds on the back wall. This room was
both mechanically and naturally ventilated, with openable windows. As with bay A, the bay
was accessed through a set of double doors, which were left open at all times. To the left of
this entrance were two rubbish bins for chemical and general waste, and round the corner
was a hand washing sink, door to the ensuite shower room and lockers provided for storage
of valuables, as can be seen in Figures 6.14 and 6.16. All the same patient and carer facilities
existed in both bay A and bay B, including flat screen televisions for each bed and patient
hoists. Figure 6.15 clearly shows these patient facilities.
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Figure 6.13 4-bed bay B
Figure 6.14 Hand washing sink, door Figure 6.15 Patient bed and fold
to shower room and lockers down chair
Figure 6.16 Ward entrance with rubbish bins
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6.6.3. Single patient rooms
Two different rooms were chosen for measurements. The rooms were situated on different
sides of the building and were slightly different in terms of room design and the amount of
glazing used.
Single patient room A was opposite nurse station 2. This room was mechanically ventilated
only and had full length windows and a patio door looking out onto a balcony area. As with
4-bed bay A, the windows and door could not be opened. The room had its own ensuite
shower and toilet, and a pull down bed was provided for the child’s parent. For privacy
purposes, full length curtains could be pulled around this bed. Separate curtaining was
provided to cover the external windows and patio door and also block out the light shining
through the glazed panel of the door to the corridor. To the left hand side of the room was a
hand washing sink and two rubbish bins for chemical and general waste. Several upright
chairs were available for visitors and an easy chair next to the bed for patient or parent use.
Figures 6.17, 6.18 and 6.19 show the bed head services, glazed balcony door, and pull down
bed with the room sink and rubbish bins.
Figure 6.17 Patient bed showing bed head services
Figure 6.18 Locked door onto balcony Figure 6.19 Door to ensuite, pull down
bed, sink and rubbish bins
Flat screen
television
Patient hoist
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Single patient room B was located halfway down one of the main ward corridors, opposite the
dirty utility room and the assisted bathroom. This room was mechanically ventilated, but
unlike room A, the windows could also be opened. Room B was slightly smaller in area than
room A, but had the same facilities available for patients and their carers including a pull
down bed, flat screen television and a patient hoist, which could be used to hoist the patient
out of bed and as far as the ensuite shower room if necessary. Figures 6.20, 6.21, 6.22 and
6.23 show the patient bed, sink and rubbish bins, the pull down bed and the patient hoist in
room B.
Figure 6.20 Patient bed and opening windows Figure 6.21 Rubbish bins and hand
washing sink
Figure 6.22 Pull down bed Figure 6.23 Flat screen television
6.7. Equipment and microphone positioning
Apart from the issue of cleanability, which was discussed in Chapter 5, care was taken over
the positioning of the microphone and associated equipment so as to minimise its impact on
staff duties and patient care. It was decided that to record comparable noise levels the
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microphone should be located in similar positions in similar locations (e.g. similar positioning
in two single rooms). Figure 6.6 shows the ward layout and microphone positions which are
discussed in the followed sections.
6.7.1. Nurse stations
As the nurse stations were busy areas, it was important that the microphone was positioned
where it was not likely to be knocked, and yet could collect comparable measurement data. In
both cases the microphone was placed on a shelving unit, 2.1 m high, pointing down at the
nurse station. The microphone position is shown by the star symbol on Figures 6.24 and 6.25.
Figure 6.24 Microphone position at Figure 6.25 Microphone position at
nurse station 1 nurse station 2
6.7.2. Four bed bays
The four bed bays presented more of a problem regarding microphone positioning. It was not
possible to position the measurement equipment close to a bed head, as there was too much
medical apparatus situated there. It was also felt by the ward manager that the patient / family
would find having the microphone so close rather intrusive. Another consideration was that
when moving the beds, equipment would easily be knocked and potentially damaged.
As measurements were to be made in two 4-bed bays, it was also necessary to find a position
in each ward that would yield comparable sets of measurements. A set of lockers 2 m high,
which were used by the parents for storage of valuables, were identified as a possible
location. These lockers, shown in Figure 6.26, were located at the back of each ward next to
the ensuite bathroom door and offered a comparable position in each bay.
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Figure 6.26 4-bed bay B with microphone placed on top of lockers
6.7.3. Single patient rooms
As with the 4-bed bays it was not practical to position the microphone close to the bed head.
A fixed cupboard housing the parents’ pull down bed was identified as a comparable location
in each room. As shown in Figures 6.27 & 6.28, the microphone was positioned 2 m from the
ground pointing down into the rooms.
Figure 6.27 Single patient room 1 Figure 6.28 Single patient room 2
with microphone position shown with microphone position shown
6.8. Other considerations
6.8.1. Identifying the optimal ‘level above’ setting for trigger files
As discussed in Chapter 5, the use of observers to identify sources of high level noise was
not practical in this study. An alternative method of identification was to make use of the built
in ‘level above’ trigger functionality of the sound level meter which creates a short audio file
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each time the LAmax parameter exceeds a specified threshold. Once the data is transferred to
a PC for analysis, each audio file can be reviewed and the sources of the high level noise
identified.
To determine the settings needed for the optimal use of this feature, various threshold and
audio quality settings were tested during the first measurement periods. Due to the limited
storage capacity of the sound level meter (2 Gb) it was important that the number and the
size of the trigger files created did not exceed this capacity before the completion of the
measurement period. If this did occur the sound level meter would simply stop part way
through a five day measurement period, resulting in a loss of data. After some
experimentation, a threshold of 70 dB LAmax was found to be the most workable setting, which
meant that each time the value of LAmax exceeded 70 dB an audio file was created. Further
detailed technical information on the use of trigger files can be found in Section 10.2.
6.8.2. Publicising the study
Some weeks before the study commenced, five laminated advertising posters were displayed
throughout the ward common areas. These posters explained in simple terms why and how
the study was being undertaken, and were aimed at both staff and parents / patients. In
addition to these posters the ward manager personally discussed the study with all his staff
during staff meetings.
It was felt that it was of utmost importance that as much information as possible was
provided. This would help to avoid any unnecessary suspicion or animosity once the
microphone was visibly introduced into the ward environment. If staff and parents / patients
were informed some time before the equipment was introduced, it was unlikely that their
behaviour would change as a result (known as the Hawthorne Effect, discussed in Section
3.2.1), as they would fully understand the reasons for the study and not feel under scrutiny
themselves.
A copy of the publicity poster can be seen in Appendix A.
6.8.3. Reverberation time measurements
As occupancy levels in Sky Ward reduced during the weekend, leaving several single rooms
and one 4 bed bay empty, it was possible to take advantage of this and make some
reverberation time measurements using an Impulse Response Method with balloon bursts as
the source. Measurements could not be made in the common areas such as nurse stations
and hallways, as the ward was still occupied in part and this would have disturbed both staff
and remaining patients.
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6.9. Questionnaire survey considerations
Information sheets and questionnaires were handed out to the staff on an ‘away day’ out of
the ward. This was suggested by the ward manager as it was thought that this approach
would yield the best response rate. The sample set for the staff study was fairly small, as the
total number of full time staff working on this ward was only 12. Every full time member of
staff completed the questionnaire survey.
Many of the children on this ward were too young to complete the questionnaire themselves.
After discussion with the ward manager, it was decided that the questionnaires would be
given to the accompanying parents, who were given the option of completing the
questionnaires on their own or jointly with their child (age and medical condition permitting). It
was felt important that the parent / patient had been present on the ward for over 24 hours to
give sufficient time for the individual(s) to form an opinion of the noise environment during the
day and the night. The first section of the patient questionnaire was changed slightly to
capture information about both the parent and patient, with an additional question to establish
whether the parent completed the questionnaire with or without input from their child.
The patient information sheets and questionnaires were handed out by the ward clerk to the
parents of the patients on the ward. In total 31 completed parent / patient questionnaire
responses were received.
Copies of the patient / parent and staff questionnaires are shown in Appendix A.
6.10. Overall acoustic survey results
Table 6.1 shows the locations and the time periods of all measurements made. It should be
noted that ‘1 week’ is defined as one set of week day data (Monday to Friday), weekends
having been excluded from the measurement period for the reasons given in Section 6.5.1.
Table 6.1 Measurement location and time interval
Position Length of measurement period
Nurse station 1 2 consecutive weeks (10 days)
Nurse station 2 1 week (5 days)
4-bed bay A 2 consecutive weeks (10 days)
4-bed bay B 1 week (5 days)
Single room A 1 week (5 days)
Single room B 1 week (5 days)
Overall noise measurements of A-weighted equivalent sound pressure levels (LAeq) for 24
hours, day time and night time were recorded, the day and night periods being defined by the
WHO guidelines (Berglund et al, 1999), where day time is specified as 07.00 to 23.00 and
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night time as 23.00 to 07.00. Table 6.2 shows the average LAeq measured for 24 hour, day
and night time periods at each location.
Table 6.2 Average LAeq measured for 24 hour, day and night time periods at each location
Position in ward Weekday average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Nurse Station 1 Week 1 56.6 58.3 47.2
Nurse Station 1 Week 2 54.3 56.0 46.2
Nurse Station 2 Week 1 58.9 60.4 51.6
4-Bed Bay A Week 1 50.2 51.7 43.4
4-Bed Bay A Week 2 52.3 54.0 41.9
4-Bed Bay B 50.4 52.2 39.5
Single Patient Room A 50.4 52.2 34.8
Single Patient Room B 56.6 58.2 47.8
A summary of the day and night time average levels (averaged over all the measurement
days for each location) are presented in Table 6.2 are presented graphically in Figure 6.29 for
clarity. It can be seen that without exception, all levels exceed those suggested in the WHO
guidelines (30 dBA LAeq for day and night). Levels measured at the nurse stations and in the
4-bed bays are shown to be fairly consistent, with night time levels on average 10 dB lower
than those measured during the day. Single patient rooms, however, are much less
consistent during both the day and night. Detailed results of levels measured at the nurse
stations are discussed in the next section, with further results from the 4-bed bays shown in
Section 6.12 and from single patient rooms in Section 6.13.
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0
10
20
30
40
50
60
70
Nurse Station 1 Nurse Station 2 Single Room A Single Room B 4 Bed Bay A 4 Bed Bay B
So
un
d P
ressu
re (
dB
A)
Day time
Night time
Figure 6.29 Average day and night LAeq levels measured at each location
6.11. Nurse stations
Figure 6.30, shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours at the two nurse
stations (means of total number of measurement days). It can be seen that the levels at nurse
station 2 are consistently higher than those measured at nurse station 1. This is as we would
expect as this nurse station is significantly larger in size, with more staff working in this area.
The levels follow very consistent patterns suggesting that the daily ward routines which
contribute to the noise levels are similar at both locations.
Interestingly, background levels at night (shown in terms of LA90,1hr) are slightly lower for nurse
station 2, even though the LAeq,1hr levels are higher at this nurse station. This could be affected
by the level of airflow from the mechanical ventilation system. Although controlled centrally in
the ward, noticeable differences were found between levels of airflow in different ward
locations. This is discussed further in Section 6.15.2.
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30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
, 1
hr)
Time (24h:00)
Nurse Station 1 LAeq Nurse Station 2 LAeq Nurse Station 1 LA90 Nurse Station 2 LA90
Day timeNight time
Figure 6.30 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations
6.11.1. Sources of high level noise
As discussed in Section 6.8.1, sources of high level noise were identified from the trigger files
captured by the sound level meter during the measurement period. The threshold for this data
capture was set to 70 dB LAmax. By reviewing each file it was possible to build up an
understanding of the types of high level noise sources present, and, by analysing the data
further, understand the impact of a particular noise event on the average noise levels.
A summary of high level noise sources identified at the nurse stations is given below:
� Staff to staff conversation
� Staff talking on the telephone
� Staff talking with patients
� Patients talking
� Ward doorbell
� Nurse call
� Internal telephone ringing
� Patients crying out
� Desk drawers
� Footsteps
� Laughter
� Furniture scraping on the floor
� Coughing
� Replacing the telephone receiver
� Medical equipment alarms
� Mobile phones ringing
� Closing ring binders
The ward manager was particularly interested in capturing occurrences of a number of ward systems
which were considered to be excessively loud. The nurse call system, internal telephone and the door
bell were all cited. Trigger files collected at the nurse stations were analysed to find the average
maximum levels of these systems. This data was captured during the first three weeks of the pilot
study and in some cases was incomplete due to initial equipment configuration problems. However,
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enough data was collected to provide a good indication of the true levels of these systems. This is
discussed further in the following paragraphs.
Nurse call
When a patient presses the nurse call button by their bed, a light flashes outside their bay or room, a
tone is emitted through the speaker behind each nurse station and information is displayed on the
console on the nurse station desk, as shown in Figure 6.31. The tone continues until the nurse
attends to the patient and cancels the call by the bedside.
Figure 6.31 Nurse call console
The microphone at nurse station 1 was positioned 3 m from the wall speaker. The levels and number
of occurrences of the nurse call which created trigger files were noted and the maximum levels were
arithmetically averaged over the five day measurement period. The distribution of the LAmax levels is
shown in Figure 6.32. In total there were 115 instances of the nurse call tone captured, resulting in an
average maximum value of 81.3 dB LAmax. The highest percentage (45%) of occurrences fell into the
LAmax level category of 82 to 84 dB. There was no noticeable difference between the levels measured
during the day or night, which was interesting as it was thought that the system had a night time
setting which lowered the volume of the tone emitted.
0
10
20
30
40
50
60
72 - 74 74 -76 76 -78 78 - 80 80 - 82 82 - 84 84 - 86
Nu
mb
er
of
occ
ure
nce
s
LAmax range (dB)
Figure 6.32 The number and levels (LAmax) of occurrences of the nurse call system at nurse
station 1, measured at 3 m over 5 days
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Only a small amount of data was available for review from nurse station 2. In total 13 instances of the
nurse call were captured over a 19 hour period, again with the microphone positioned 3 m away from
the wall speaker. An average maximum value of 80.2 dB LAmax was calculated. The highest
percentage (54%) of occurrences fell into the LAmax level category of 82 - 84 dB as with nurse station1.
Internal Telephone
The microphone at nurse station 1 was positioned 3 m from the telephone on the desk. Over the five
day measurement period there were ten separate occurrences of the ringing telephone which created
trigger files. The resulting average maximum of the internal telephone was found to be 72.3 dB LAmax.
As the average maximum was close to the trigger threshold of 70 dB LAmax, it is felt that some
occurrences of the ringing telephone may not have been captured, so as such this figure may not be
accurate.
No data exists for the internal telephone at nurse station 2, but it is expected that similar levels would
have been measured.
Ward Doorbell
When the ward reception desk is unmanned, ward visitors ring the doorbell and a member of staff
remotely opens the door to the ward, which is locked for security purposes. As with the nurse call, the
ward doorbell is piped to the small speaker mounted behind each nurse station.
Only a small amount of data was available for review in this case. This was for nurse station 2 with
the microphone positioned 3 m from the speaker. In total, 42 instances of the doorbell were captured
over a 19 hour period, resulting in an average maximum value of 80.6 dB LAmax. The highest
percentage (52%) of occurrences fell into the LAmax level category of 80 to 82 dB. The distribution of
the LAmax levels is shown in Fig 6.33.
0
5
10
15
20
25
74 -76 76 -78 78 - 80 80 - 82 82 - 84 84 - 86
Nu
mb
er
of
occ
ure
nce
s
LAmax range (dB)
Figure 6.33 The number and levels (LAmax) of occurrences of the ward doorbell at nurse station 2,
measured at 3 m over 19 hours
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Although data was only available from nurse station 2, it is expected that similar levels would have
also been measured at nurse station 1.
All the reported levels for the three ward systems are typical of those to which a staff member would
be exposed when sitting at the nurse station desk. Figure 6.34 illustrates the difference between
these calculated maximum levels and the average day and night time levels measured at the nurse
stations. It can be seen that the average LAmax levels exceed the day time LAeq,16hr by between 14 and
23 dB, and the night time LAeq,8hr by between 24 and 33 dB.
30
35
40
45
50
55
60
65
70
75
80
85
90
Nurse Call Internal Phone Doorbell
So
un
d P
res
su
re (d
BA
)
80.6 dB LAmax80.8 dB LAmax
72.3 dB LAmax
Figure 6.34 Average LAmax of the nurse call system, internal telephone and ward doorbell
When questioned, staff cited the ward doorbell, nurse call and internal phone as the most annoying
sources of noise (see Section 6.16.2). Staff also rated these systems as the noise sources which
most interfered with their ability to carry out their job effectively.
6.12. Four bed bays
Figure 6.35 shows the averaged LAeq,1hr and background levels (LA90,1hr) levels over 24 hours for the
two 4-bed bays. It can be seen clearly that the averaged LAeq,1hr levels were very consistent over time,
with a day time level of around 53 dB LAeq,16hr, over 20 dB higher than the WHO guidelines. The night
time average was found to be 11 dB lower than that measured during the day, around 42 dB LAeq,8hr.
This was still over 10 dB higher than the acceptable level stated in the WHO guidelines. Surprisingly,
there is a 5 dB discrepancy in background levels between the two bays during the night. This can be
partly explained because of the ventilation systems in use on the ward. Bay A is mechanically
Average day time level at nurse station: 58.2 dB LAeq,16hr
Average night time level at nurse station: 48.3 dB LAeq,8hr
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ventilated only, and in bay B the windows can also be opened. It is possible that opened windows
may account for part of this discrepancy.
The figure also shows that the WHO day / night division is a poor fit, with noise levels tailing off earlier
in the evening, at around 21.00. This of course could be attributed to the fact that this is a children’s
ward and as such a day and night division specifically for a ward of this type may be more
appropriate.
20
30
40
50
60
70
So
un
d P
res
su
re (L
Ae
q,1
hr)
Time (24h:00)
4 Bed Bay A LAeq 4 Bed Bay B LAeq 4-Bed Bay A LA90 4-Bed Bay B LA90
Day timeNight time
WHO GUIDELINES
Figure 6.35 Average LAeq,1hr and LA90,1hr levels over 24 hours for 4-bed bays A and B
6.12.1. Sources of high level noise
The sources of high level noise were identified from the trigger files captured by the sound level meter
during the measurement periods. The overall numbers of files for the three periods were similar, with
942 and 1002 files recorded in 4-bed bay A during measurement weeks 1 and 2 respectively, and 870
recorded in 4-bed bay B.
Building up a full picture of the sources of high level noise by reviewing the trigger files was at times
difficult. Many of the sources were fairly close to the microphone making it hard to build up a complete
picture of what was happening in the bay. As will be seen in Section 6.13 this was not the case in the
single rooms, where it was possible to identify some patterns with only one patient and parent
present.
Figure 6.36 shows the numbers of occurrences of each noise source type as a percentage of the total
number of files captured. It can be seen that for each measurement period a high percentage of
trigger files were listed as ‘unidentified’. These were commonly caused by visits by a clinician to a
patient. Often these visits were to provide patients with their medication; to undertake medical
examinations; or to redress wounds. During this time bed rails were moved and beds were readjusted
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and repositioned, leading to the creation of a number of trigger files which were very difficult to identify
accurately. With younger patients especially, a visit by a clinician often led to a great deal of
screaming or crying. Patients were then made comfortable, leading to another set of high level noises
which were again difficult to identify and categorise. On occasions it was obvious that certain noise
events were related to a patient procedure, and were noted as such; however this was not always the
case.
Specific high level noise events which were clearly identifiable in these two bays were the door to the
ensuite facilities in 4-bed bay A (because of the loud locking mechanism); medical equipment alarms;
patients crying out; conversation; coughs and sneezes; and the use of rubbish bins, both in the
ensuite shower room and on the ward.
0 10 20 30
Unidentif iable
Conversation between staf f
Conversation between staf f and parents
Cough / sneeze
Dustbin
Laughter
Crying
Curtains
Parents / patients talking
Medical Equipment
Furniture Scraping
Squeak of shoes on f loor
Desk drawers / cupboard doors
Cleaning
Meal time
Visiting time
Door to ensuite bathroom
Patient procedures
Accessing lockers
Patient vomiting
Parent shouting for nurse
Children's entertainer
4 Bed Bay A Week 1 4 Bed Bay A Week 2 4 Bed Bay B
Figure 6.36 Percentages of high level noise events by type measured in 4-bed bays A and B
Figure 6.36 shows that particularly large differences can be seen between the percentages of trigger
files created over the measurement intervals in the two bays, especially those caused by patient
procedures, medical equipment and patients crying. All these are of course dependent on the severity
and type of the patient’s condition. Patients in Sky Ward undergo different levels of surgery and as
such it is not surprising to find large variation in the numbers of occurrences of high level noise
events.
There are notable differences in the use of the door to the ensuite bathroom from week 1 to week 2 in
4-bed bay A. The use of the ensuite may be related in part to the mobility of the patients and also to
the numbers of parents staying on the ward, so these factors may account for the change.
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As discussed earlier in this section, many of the trigger files categorised as ‘unidentified’ are as a
result of visits by clinicians. It is interesting to note that the week with the highest percentage of
unidentified trigger events is the week with the highest percentage of medical equipment alarms and
patient procedures, suggesting more clinical activity on the ward during this week.
Surprisingly, trigger files caused by visiting time are only captured during week 2 in 4-bed bay A. On
reflection, this may be very dependent on the location of the microphone. Only visitors to the bed
situated next to the microphone are likely to cause noise of a sufficient level for the trigger files to be
created.
6.13. Single patient rooms
Figure 6.37 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the two single patient
rooms. It can be seen that, unlike the 4-bed bays, the levels in the two single patient rooms were very
inconsistent, with an average difference in the LAeq levels of 6 dB during the day and 13 dB at night.
The night time background levels in single room B can be seen to be low, at around 29 dB LA90,1hr,
around 5 dB less than for single room A. This may suggest differences in the consistency of airflow of
the mechanical ventilation system, which is discussed further in Section 6.15.2.
The dotted line indicates the WHO specified average noise level for ward accommodation. It can be
seen that the night time levels in single patient room A were close to the recommended WHO levels,
but levels at other times were much higher, with a day time average LAeq,16hr of 58.2 dB in single room
B; almost 30 dB higher than the WHO recommendations.
20
30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
, 1
hr)
Time (24h:00)
Single Room A LAeq Single Room B LAeq Single Room A LA90 Single Room B LA90
Day timeNight time
WHO GUIDELINES
Figure 6.37 Average LAeq,1hr and LA90,1hr levels over 24 hours for single patient rooms A and B
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The next section looks at the sources of high level noise in each room in an attempt to understand the
inconsistencies found.
6.13.1. Sources of high level noise
By identifying the sources of high level noise from the trigger files, it was possible to build up a picture
of the type of events which caused the measured levels to be so different between the two single
rooms. Figure 6.38 shows the percentages of each noise source type as a percentage of the total
number of files captured.
The overall numbers of high level noise events in each room were very different. There were nearly
five times more recorded high level noise events in room B (2898) than room A (608). This can be
explained in part by the severity and type of the patient’s condition. The patient occupying room B for
the majority of the measurement period required a large amount of clinical intervention during their
stay which resulted in 35% of all high level noise events being attributed to medical equipment alarms
and 16% to patient procedures (visits by clinicians to provide a level of care).
It can also be seen that the use of televisions and mobile phones caused a number of high level noise
events in room B, but not in room A. During the measurement period in room B there were 124
instances (4%) where the television level was greater than 70 dB, and there were 224 instances (8%)
where conversations on mobile phones were measured at this level or above.
0 5 10 15 20 25 30 35
Unidentif iable
Conversation between staf f
Conversation between staf f and …
Cough / sneeze
Dustbin
Laughter
Crying
Parents / patients talking
Medical Equipment
Furniture Scraping
Cleaning
Meal time
Visiting time
Talking on mobile phone
TV
Patient procedures
% occurance of event type
Single Patient Room B Single Patient Room A
Figure 6.38 Percentages of high level noise events by type for single patient rooms A & B
To illustrate the impact of certain high level noise events on the average noise level within a room,
certain typical events in single patient room A were analyzed in further detail. Table 6.3 presents the
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event LAeq and LAmax. To put these levels into context the day time average noise levels measured in
this bay were 52.2 dB LAeq,16hr.
Table 6.3 Average and maximum noise levels of identified events in single room A
LAeq LAmax
Fluid Pump
Alarm71.6 89.1 19.4 36.9
Room Cleaning 54.4 79.3 2.2 27.1
Visit to a patient 57.6 75.7 5.4 23.5
Bin Bag
Changing60.4 75.5 8.2 23.3
Patient
Procedure59.2 81.5 7.0 29.3
Rubbish Bin Impulsive 80.6 Impulsive 28.4
Event (dB)Level above room day time LAeq
Event LAeq Event LAmax
It must be stressed that the events in Table 6.2 are shown for illustration purposes. They are not
necessarily representative of every event of that type. However, it is interesting to see that the
maximum noise levels measured were as high as 89 dB LAmax. Both the fluid pump and the rubbish
bins caused levels which were over 80 dB LAmax and exceeded the average day time noise level by
nearly 30 dB.
6.14. Establishing a representative measurement interval
One aim of the pilot study was to establish a representative measurement period which could then be
used throughout the main study. Many reviewed studies measured noise levels for a single 24 hour
period. It was considered unlikely that a randomly chosen 24 hour interval would be representative of
typical noise levels on a hospital ward. This is further illustrated by Figure 6.39 which shows the
noise level fluctuations over 24 hours for five days at nurse station 1. It can be seen that if, for
example, Thursday had been chosen for a 24 hour measurement interval, it would have yielded very
different results than if Tuesday had been chosen. In fact there would be a difference of 5.4 dB during
the night time LAeq,8hr and 5 dB difference during the day time LAeq,16hr.
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30
40
50
60
70
So
un
d P
ressu
re (
dB
A)
Time (24h:00)
Friday LAeq Monday LAeq Tuesday LAeq Wednesday LAeq Thursday LAeq
Figure 6.39 LAeq,1hr levels measured over five consecutive days at nurse station 1
Given that a single 24 hour period did not appear to be representative, a five day measurement period
was then considered (weekdays only due to low occupancy during weekends). Data was available for
two consecutive five day intervals at both nurse station 1 and 4-bed bay A.
Figure 6.40 shows arithmetically averaged LAeq,1hr values from Monday to Friday, for two consecutive
weeks at nurse station 1. It can clearly be seen that the averaged levels are similar in both level and
fluctuation. A χ2 goodness of fit test showed that the two datasets do not differ significantly at the 1%
level. Therefore it may be assumed that a five day measurement period gives reliably representative
data to describe the noise climate at this nurse station.
30
40
50
60
70
So
un
d P
ress
ure
(d
BA
)
Time (24h:00)
Nurse Station 1 Week 1 Nurse Station 1 Week 2
Day time
Night time
Figure 6.40 Average LAeq,1hr levels over 24 hours for week 1 and week 2 at nurse station 1
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Data was also available for two consecutive five day intervals for 4-bed bay A. Figure 6.41 shows
averaged LAeq,1hr values from Monday to Friday, over a period of two consecutive weeks in 4-bed bay
A. It can clearly be seen that the averaged levels are similar in both level and fluctuation, again
suggesting that a weekday measurement interval may be representative.
The χ2 goodness of fit test again showed no statistically significant difference between the two
datasets at the 1% level.
20
30
40
50
60
70
So
un
d P
ressu
re (
dB
A)
Time (24h:00)
4-Bed Bay A Week 1 4-Bed Bay A Week 2
Day time
Night time
Figure 6.41 Average LAeq,1hr levels over 24 hours for week 1 and week 2 for 4-bed bay A
It has therefore been shown that, as with the nurse station, a five day measurement period is a
suitably representative interval for 4-bed bay A.
These results suggest that a five day period at a nurse station or in patient accommodation is
sufficiently long to give reliable noise level data.
6.15. Other measured acoustic parameters
6.15.1. Reverberation times
It was decided that it would be possible to make some reverberation time (RT) measurements in the
unoccupied ward accommodation during the weekend, without causing undue disturbance to staff and
patients. Balloon bursts from thick latex 14 cm balloons were chosen as the noise source. As
discussed in Section 5.3.8 the number of source and receiver positions used were in accordance with
the British Standard BS EN ISO 3382-2 (1998) for ‘engineering’ work.
Table 6.4 shows the measured RT20 values (to the nearest 0.05 s) in three rooms, together with room
volume, ceiling area (which is the main area of acoustic absorbency) and the glazing area. This
building was built in line with the previous acoustic design guidance, HTM 2045 (NHS Estates, 1996),
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as discussed in Section 6.4. All the measured RT values would be considered to be very low; well
within the recommendations of this guidance.
Table 6.4 Reverberation times measured in different ward accommodation
Room
Description
Volume (m
3)
Ceiling area (m
2)
Glazing area (m
2)
RT20 (s) @ 1kHz
4-bed bay B 168.5 62.4 9.1 0.28
Single room A 57.7 19.5 10.5 0.32
Single room B 40.3 14.9 5.6 0.26
It can be seen that the RT in single room A is slightly longer that the RTs in the other two areas. This
is probably due to the larger area of glazing in room A, as described in Section 6.6.3.
6.15.2. Ambient noise levels
30 second measurements of ambient noise levels were made in two empty single patient rooms and
one empty 4-bed bay during the day time. The results are shown in Table 6.4.
Table 6.5 Ambient noise levels measured in unoccupied patient accommodation
Room description
Ambient noise level (LAeq)
4-Bed Bay B – windows closed
35.0 dB
4-Bed Bay B – windows open
37.5 dB
Single patient room A – windows closed
31.6 dB
Single Patient Room B – windows closed
37.7 dB
Single patient room B – windows open
40.3 dB
Table 6.5 shows a difference of 6.1 dB between the quietest and noisiest rooms with the windows
closed. This is thought to be predominantly due to the amounts of low level air flow through the ceiling
vents. In some rooms the air flow was much more noticeable than in others. The mechanical
ventilation system on this ward is controlled centrally, and not on a room-by-room basis, and so it
would be expected that airflow in all rooms would be constant. However, in discussions with ward
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staff, the differences in air flow and also heat levels were mentioned on several occasions. This
suggests the mechanical ventilation system may not be working as designed.
Rooms situated on the west side of the building have windows that can be opened. It can be seen in
Table 6.4 that there is an increase in ambient noise levels of approximately 2.5 dB when a window is
opened. This increase is thought to be mainly caused by traffic noise, as the hospital is situated in
central London.
6.16. Results of the staff questionnaire surveys
The design of the questionnaire surveys was discussed in detail in Section 5.4 and the administration
of the questionnaires in Section 6.9.
In total 12 staff completed the questionnaires. The following sections discuss results from the
questionnaires and show the differences between staff perceptions.
6.16.1. Staff profile
To establish certain attributes about the staff, the first section posed a number of basic questions. Out
of the 12 respondents only 17% were male and 83% were female. The majority of staff were relatively
young, with 75% in the age group 20-30, 17% in the age range 31-40, and 8% in the age range 41-
50. The average length of time that staff had worked on the ward was just over 2 years, but the length
of time working at Great Ormond Street Hospital was longer for some staff, suggesting internal
transfer from other wards.
6.16.2. Noise annoyance and interference
General feelings of noise annoyance were investigated by asking staff to what extent they were
annoyed by noise. It can be seen from Figure 6.41 that 18% of respondents felt moderately annoyed
by noise, with 45% of respondents ‘very much’ annoyed by noise in their work environment. Thus in
total 63% of staff were moderately or greatly annoyed by noise. It is interesting to note that no-one
selected the ‘extremely’ annoyed category. It should be remembered that all 12 permanent members
of staff on the ward completed the questionnaire so it is not the case that responses were received
only from those concerned about noise.
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Figure 6.41 Distribution of the extent of staff annoyance
Staff were asked to rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating
‘not at all annoying’ and 4 indicating ‘a great deal’. Figure 6.42 shows the percentages of staff who
rated a noise event with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the
event.
0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
General conversation
Nurse call
Doorbell
Footsteps
Medical Equipment
Cleaning
Rubbish bins
Trolleys
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Visiting time
% of staff rating annoyance event 2 or above
Figure 6.42 Percentage of staff rating an annoyance noise event with a 2, 3 or 4
Figure 6.42 clearly shows that the four most annoying sources of noise to staff are the ward doorbell,
nurse call, internal telephone and medical equipment alarms, which were all rated by over 80% of
staff as annoying. This response is consistent with the views of the ward manager with regards to
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these systems. Visiting time and talking on mobile phones are found to be the next most annoying
sources of noise, rated by over 60% of staff.
Respondents were asked to what extent noise interfered with their ability to work effectively. Figure
6.43 shows that 42% felt noise ‘moderately’ interfered with their ability to work; with only 8% feeling
that noise interfered ‘very much’. It appears from these responses that noise interference is perceived
to be less of an issue than noise annoyance.
Figure 6.43 Distribution of the extent of noise interference with work
Staff were also asked to rate how much each noise event interfered with their ability to carry out their
job effectively (again the rating scale of 0 to 4 was used). Figure 6.44 shows the percentage of staff
who rated a noise event with a 2, 3 or 4, and as such it could be said that this noise event interfered
to some extent with their ability to carry out their job effectively.
Figure 6.44 shows clearly that as with noise annoyance, the four sources of noise which were felt to
cause the most interference were the nurse call and internal telephone (both rated by over 80% of
respondents), and the ward doorbell and medical equipment alarms, (both rated by over 70% of
respondents). Talking on mobile phones is ranked fifth, as with noise annoyance, with 50% of
respondents finding this activity interferes with their ability to carry out their job effectively.
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0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
General conversation
Nurse call
Doorbell
Footsteps
Medical Equipment
Cleaning
Rubbish bins
Trolleys
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Visiting time
% of staff rating interference event 2 or above
Figure 6.44 Percentage of staff rating an interference noise event with a 2, 3 or 4
The corresponding LAmax values for the doorbell, nurse call and internal telephone are indicated on the
figure. It can be seen that all the values for the doorbell and nurse call are higher than would be
expected in a ward environment, which is again consistent with the views of the ward manager.
6.16.3. Important sounds
To aid understanding of which sounds were felt by staff to be important to be heard in order to carry
out their jobs effectively, staff were asked to rate different noise events on a scale of 0 to 4, where 0
indicated ‘not at all important’ and 4 indicated ‘extremely important’.
It can be seen in Figure 6.45 that ‘medical equipment alarms’ are considered by staff to be the most
important noise events with a mean value of nearly 3.5 out of the maximum 4, followed by the ‘nurse
call’ and ‘patients calling out’ with means of around 3.0. Given the annoyance / interference felt by the
staff with regards to the nurse call, perhaps a different type of alert is more suitable, perhaps making
use of silent technologies such as a personal handset which vibrates. Given the necessity for staff to
be aware of the nurse call, careful consideration must be given to ensure that a suitable system is
found that is not so subtle that it could be missed by staff.
77.9 dB LAmax
80.6 dB LAmax
72.3 dB LAmax
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Figure 6.45 Mean importance rating of certain noise events
6.17. Patient questionnaires
In total 31 parents / patients completed the questionnaires. The following sections discuss results
from questionnaires and examine the parent / patient perceptions of the noise environment.
6.17.1. Parent / patient profile
Out of the completed questionnaires, 55% were filled out by parents alone and 45% by the parent
with input from their child. Of those questioned, 10% of the parents were male and 90% were female,
with 39% male patients and 61% female. Figures 6.46 and 6.47 show the distribution of ages of both
parents and patients. It can be seen in Figure 6.46 that the majority of parents were aged between 31
and 50 years, with Figure 6.47 showing a fairly even split in relation to the patients’ age, apart from
children under five years old.
0
10
20
30
40
50
20-30 31-40 41-50 51-60 60+
% o
f re
po
nd
en
ts
Age range (years)
0
10
20
30
40
< 5 5-10 11-13 14-18
% o
f re
po
nd
en
ts
Age range (years)
Figure 6.46 Parents by age bracket Figure 6.47 Patients by age bracket
Out of those questioned, 87% were staying in a 4-bed bay, with an average length of stay of four
days.
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6.17.2. Noise annoyance
The next section of the questionnaire considered day time noise annoyance and night time
disturbance. The questionnaire sought to identify the sources of noise that may annoy or disturb
patients. Respondents were given two lists of noises and were asked to rate the day time annoyance
and night time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4
indicated a great deal). Several lines were left blank at the bottom of the lists for patients to add and
rate additional noise sources.
Parents / patients were first asked how they perceived the day time noise environment on the ward.
Figure 6.48 shows that the highest number of those questioned, 58%, felt that the ward was ‘a little
noisy’ during the day, 32% felt that the ward was quiet or very quiet, while 10% felt it was very noisy.
It may be interesting to note that no-one selected the ‘extremely noisy’ category.
Figure 6.48 Distribution of the extent of parent / patient annoyance during the day time
Although there was a high percentage of people that considered the ward to be a ‘little noisy’ only
23% of respondents were actually annoyed by noise during the daytime.
The patients who had indicated that they were annoyed by noise during the day, were then asked to
rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’
and 4 indicating ‘a great deal’. Figure 6.49 shows the percentage of patients who rated a noise event
with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the event. As can be
seen clearly the percentages of those annoyed by any events were very low, with the largest
percentage of respondents (25%) annoyed by medical equipment alarms, followed by noise from TV
and radio use rated by 19%, and mobile phones ringing rated as annoying by 16% of respondents.
Day time annoyance Day time annoyance
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0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
General conversation
Nurse call
Doorbell
Footsteps
Medical Equipment
Cleaning
Rubbish bins
Trolleys
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Visiting time
% of parents / patients rating annoyance event 2 or above
Figure 6.49 Percentage of parents / patients rating an annoyance noise event with a 2, 3 or 4
Patients were next asked how they perceived the night time noise environment on the ward. Figure
6.50 details the responses, showing that during the night 45% of those questioned felt that the ward
was either ‘very quiet’ or ‘quiet’. The highest percentage, 42%, found the ward to be ‘a little noisy’ and
13% felt that the ward was ‘very’ or ‘extremely noisy’.
Figure 6.50 Distribution of the extent of parent / patient disturbance during the night time
Night time disturbance
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When questioned whether they were actually disturbed by noise at night, 70% of respondents said
they were disturbed.
Patients who had indicated that they were disturbed by noise during the night were asked to rate the
annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’ and 4
indicating ‘a great deal’. Figure 6.51 shows the percentage of patients who rated a noise event with a
2, 3 or 4, and as such could be said to be more than a little disturbed by the event.
0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
General conversation
Nurse call
Doorbell
Footsteps
Medical Equipment
Rubbish bins
Trolleys
TV / radio
Mobile phones ringing
Talking on mobile phones
Other patients cying out
% of parents / patients rating disturbance event 2 or above
Figure 6.51 Percentage of parents / patients rating a disturbance noise event with a 2, 3 or 4
As with day time annoyance, medical equipment alarms were again rated as the most disturbing
noise source, in this case, by over 50% of respondents. The second most disturbing noise source was
banging doors (35%), followed by TV and radio usage (29%).
6.17.3. Positive sounds
Looking at sound in a positive rather than in a negative light, parents / patients were asked if there
were any sounds that they found comforting. 94% of answers were left blank with only two completed
responses: ‘the footsteps of nurse coming to reset instruments’; and ‘people talking / relatives visiting’.
Respondents were asked if they felt that there was ever too little sound in a room. Only 7% of those
completing the question felt there was, but surprisingly these respondents were in 4-bed bays.
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6.17.4. Privacy and ease of hearing
Parents / patients were asked whether high background noise might make it difficult to hear doctors
and nurses who talk to them. The majority of respondents, 81%, said they could ‘always clearly hear
what people say’, with only 19% feeling that ‘occasionally high levels of noise can make it hard to
hear’. Interestingly one of these respondents was staying in a single room. No respondent reported
any hearing impairment.
Conversational privacy was investigated by asking whether the parent / patient felt that they could
have a private conversation at their bedside. 29% said that they did not feel they could speak
privately, all of whom were in 4-bed bays. Out of those who said they felt they could speak privately,
38% of people said they would use their normal voice, with 62% feeling that they would need to lower
their voice.
6.17.5. Patient’s questionnaire comments
Parents / patients were invited to make additional comments at the end of the questionnaire if they
wished. Many of the comments made were in relation to the use of radios and TVs without
headphones. A detailed list of these comments is shown in Appendix B.
6.18. Summary of results
This section summarises the main findings from the pilot study:
� Measurements made at the nurse stations and 4-bed bays were found to be consistent, with
day time levels at the nurse stations around 58 dB LAeq and levels in the 4-bed bays around
52 dB LAeq.
� Levels measured in the single patient rooms averaged around 50 dB LAeq, but were much
less consistent. The differences in measured levels were affected in part by the amount of
care required by the patient, and by the behaviour of the individuals in the room. For example,
the use of television at high volume and mobile phone conversations both contributed to
higher levels.
� It was more difficult to build up a complete picture of high level noise events in the multi-bed
accommodation. In the single rooms it was possible to identify some patterns as there was
generally one patient and parent present, but in the 4-bed bays it was thought that more
localised sounds were creating the trigger files.
� Night time levels were in general found to be 10 dB lower than day time levels.
� Reverberation times measured in patient accommodation were very low, due in part to the
good acoustic properties of the ceiling tiles used. However, the use of solid plaster ceilings in
hallways and at the nurse stations may lead to longer reverberation times and higher noise
levels in these areas.
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� Ventilation noise was on occasions noticeably loud, and was not controlled on a room-by-
room basis.
� 63% of staff questioned were ‘moderately’ or ‘very much annoyed by noise in their work
environment, and 50% felt noise ‘moderately’ or ‘very much’ interfered with their ability to
work.
� Staff questionnaire responses consistently found that the internal telephone, nurse call, ward
doorbell and medical equipment alarms caused the most annoyance and interference. This
suggests that a level of noise control should potentially be applied to these systems, or
alternatives sought.
� 70% of parents / patients were disturbed by noise at night, but only 23% annoyed by noise
during the day.
� Medical equipment alarms, banging doors and the use of television and radio were rated as
the most disturbing sources of noise to patients / parents at night. Soft door closers and the
use of headphones for television and radio usage would be a simple and relatively cheap
solution to reduce some of this annoyance. The use of medical equipment alarms could be
studied further. Some alarms may be un-necessary or are set too loud; however, a careful
balance must be sought as these alarms are rated as the most important noise sources for
staff to hear.
� Lower percentages of parents / patients rated noise annoyance and disturbance events than
the staff. This may be partly due to their not wanting to be critical as their child is unwell and
they are grateful to the staff and hospital, or because they are focussed on their child’s care
and wellbeing and noise is less noticeable than it may be in other situations.
The pilot study aimed to provide useful feedback for the redevelopment team and the ward manager
on the site. Following its completion, a full report was provided for each team member involved, and
the ward manager of Sky Ward was also informed of the relevant findings. Follow up meetings were
held with ward staff, which are discussed in the following section, and further highlighted areas that
could potentially be improved with regards to noise control.
6.19. Follow up discussions
Several meetings were held with the staff of Sky Ward to present the pilot study findings and discuss
changes that could potentially lead to an improvement in certain areas. Members of the
redevelopment team also attended the meetings. A summary of the discussions are shown below.
Television usage on the wards
Many of the patient comments indicated that one of the main issues was around the use of television /
radio without the use of headphones. Further discussion with staff regarding this issue yielded some
interesting findings and attitudes towards the use of televisions on the ward:
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� There are four flat screen TVs in each of the 4-bed bays, all suspended from the ceiling at the
end of each patient’s bed. A remote control is supplied with each TV, but it appears that all
remote controls are identical, so they control not only the patient’s TV but all four installed in
the bay. The consequence of changing a channel or adjusting the volume on one television
could be that the other televisions in the bay are affected. Staff also mentioned that the
default volume when the televisions are switched on is set very loud.
� The type of television installed on the ward requires ‘wired’ headphones, which is a difficult
option as they are positioned so far from the bed head. There are some portable DVD players
currently available which could be watched with headphones.
� Staff felt that many of the patients with special needs would not be able to wear headphones
and they appeared slightly reluctant to enforce the general use of headphones. It was felt that
some patients would be used to having the TV on all the time at home and it would not be fair
to prevent the patient from behaving in the same way on the ward; even to the extent of falling
asleep to the noise from the TV.
� Younger members of staff did not appear to consider extensive and loud use of TVs as
unacceptable and did not seem to be aware that that one patient’s behaviour might negatively
impact the others on the bay.
Banging doors
Banging doors were listed as a disturbance in the patient questionnaires. Staff mentioned that the
quiet closers on most doors did not seem to work effectively, resulting in a loud thud as the door
closed. This had recently become such a problem that staff have draped towels over doors to stop
them banging (although this has since been stopped by the ward manager).
The door of the dirty utility room was mentioned as being particularly loud and prompted further
discussion on the difficulty of entering the dirty utility room whilst carrying spillable objects. It was felt
that a kick bar on the base of the door might be more effective than an ordinary handle. The necessity
for security for the utility room was also discussed with staff feeling that the use of a swipe card or key
code system could potentially lead to even greater access problems. Many staff felt that it was
unnecessary to have security for this room at all. Single patient room 11, the staff room and kitchen
were all cited as having particularly loud doors.
The doorbell
The ward doorbell had been noted by the ward manager as being extremely loud and was shown to
be a source of interference and annoyance for staff. As a consequence, a new system had been
installed with a volume control. Although the ward manager had turned down this volume, no
difference had been perceived by the staff, who still felt it was extremely loud, especially at night.
The use of the doorbell was discussed further. Many of those ringing out of hours tended to be visiting
or staying with their children on the ward and seem to ignore the sign asking for the bell to be rung
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once. It was also mentioned that if someone leaves their finger on the buzzer for a long period, it
continues to ring. This annoys the staff immensely, especially late at night when fewer staff are
present on the ward and may be busy with other duties. Staff felt that it would be useful if the doorbell
could somehow be limited to ring once every 30 seconds.
The possibility of issuing passes was investigated. However, this has been trialled previously and
many passes were never returned to the ward. With each pass costing between £5 and £10 this
option was considered too expensive to be workable.
It was also mentioned that the security camera pointed at the ward entrance, which is installed so that
staff can identify those ringing the doorbell, is pointed at the back of the heads of those ringing. The
camera’s validity in terms of security was felt to be questionable.
Nurse Call
This was another system that was identified as being extremely loud, with no perceptible volume
change between the day and night time setting. This was still considered to be problem by the ward
staff.
Miscellaneous Alarms
The Controlled Drugs cupboard has both a light and an alarm. This alarm is found to be very
annoying by the staff.
Internal Telephones
Internal phones at the nurse stations were also shown to be an annoyance and to interfere with staff
duties. Staff felt that the phones ring a great deal and are loud. According to the members of staff
present, they can be turned down with the exception of the emergency phone, which is a fixed volume
(very loud). Various ideas for replacements were discussed, including bleepers and portable phones.
If the ward clerk is away from her desk, the main ward phone diverts onto the ward and consequently
the ward staff have to deal with the calls and pass messages back. The possibility of installing a voice
mail system for the ward clerk was discussed and considered to be a positive idea by the staff. This is
an illustration of a simple, cost effective solution that can be found by directed discussion.
Doctor’s office alarm
As discussed, Sky Ward is mechanically ventilated and the system is controlled centrally. Staff
mentioned that certain rooms are particularly warm and some particularly cold, especially if the beds
are situated directly under the ceiling vents. One room that is always very warm is the doctor’s office,
which leads to the door being constantly propped open. With the door open a very high pitched alarm
is activated, which is continually reset. This is extremely annoying to staff.
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6.20. Conclusions
The main purpose of the pilot study was to trial the proposed methodologies to ensure that meaningful
results could be obtained in line with the research proposal. Both the objective measurements and the
subjective questionnaire surveys were generally felt to be successful, with a number of specific
aspects discussed in further detail below.
� The pilot study showed that suitable microphone positions could be found, which would allow
for meaningful comparisons. However a degree of flexibility was required so as to minimise
the impact of the microphone and associated equipment on staff duties and patient care.
� Trigger files were successfully used to identify sources of high level noise, but analysis was
found to be extremely time consuming. It was felt that further consideration was needed to
ascertain the best way to present this data in the main study.
� A working week was shown to be a representative measurement interval. This interval was to
be further validated during the main study if possible.
� Both staff and patient questionnaires generally worked well, with only two questions requiring
a small amount of re-wording to ensure complete clarity.
Both the study findings and results of the follow up meetings are currently being used to positively
influence / inform the choice of systems and ward design for the next phase of the Great Ormond
redevelopment. Improvement to some of the existing systems on Sky Ward is also being investigated,
and it is hoped that some noise control measures can be taken.
The following chapters describe the main study which involved noise and questionnaire surveys in a
medical and surgical ward at Bedford Hospital and in three wards at Addenbrooke’s Hospital,
Cambridge. As part of the Bedford Hospital study, a ceiling intervention study was also carried out
and changes to sound levels and reverberation times were investigated. This is discussed in further
detail in Chapter 8.
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7. Bedford Hospital
7.1. Introduction
Two wards at Bedford Hospital were the subject of the main study, which took place over an eight
month period, from April to November 2010. Working in collaboration with the Estates team, two
inpatient wards of similar layout were chosen in the main five storey ward block. For comparison
purposes one ward was a surgical ward, the other medical. Within the study time frame a
refurbishment of the medical ward was also planned. This was of particular interest to the Estates
team, who wanted to establish the effects of changing reflective ceiling tiles for those with good
acoustic properties. The results of this change are discussed in further detail in Chapter 8.
This chapter begins by looking at the background of Bedford Hospital, providing an overview of the
acoustic design considerations of the ward block and exploring the hospital policies and equipment
usage that may affect the noise levels in the study wards. The chapter continues by examining the
two wards participating in the study individually, including their design layouts and the daily routines.
Objective results from each ward are reported, and staff and patient perceptions of the noise
environment are explored.
7.2. Background
Bedford Hospital opened in 1803, consisting of just six beds, and employing a staff of four clinicians.
Now, over two centuries later, the hospital provides 403 patient beds and has a staff of over 2000.
Services are provided for around 270,000 people in mid and north Bedfordshire and include medical,
surgical, paediatric and neonatal wards; A&E; an Acute Assessment Unit (AAU); and a specialist
cancer centre. One of the original buildings still exists, as can be seen in Figure 7.1, but there have
been many additions, many of which were built in the 1970’s and 1980’s (as seen in Figures 7.2 and
7.3). The hospital continues to expand.
Figure 7.1 Original building, Bedford Hospital (1803)
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Figure 7.2 Five storey ward block Figure 7.3 Main hospital entrance
7.3. Building acoustic design considerations
The main five storey ward block was constructed in the early 1980’s under ‘Crown Immunity’, which in
effect means that this building was exempt from building regulations. It is unknown if any acoustic
guidelines were taken into consideration during the build.
The construction of the ward block is primarily concrete, naturally ventilated and single glazed. The
two inpatient wards chosen to participate in the study are of identical layout, and situated a floor apart.
Each ward is designed around a central corridor which runs down the length of the ward. The main
patient accommodation is situated to one side of this corridor and consists of a number of open four
and six bed bays. These bays look out over the main hospital entrance, car park and several
connecting roads, one of which is a busy main road; although traffic flow is relatively slow due to
traffic lights. On the opposite side of this main corridor are the staff healthcare utilities, offices,
storerooms, a kitchen and four single patient rooms, which overlook the new maternity wing. Ward
plans are shown in Sections 7.5 and 7.6.
Both study wards have suspended ceiling grids with perforated acoustic ceiling tiles in the majority of
the multi bed bays, single rooms, offices and corridors; although there are exceptions, further details
of which are discussed in Section 7.6.2. Other acoustic absorbency is provided by the fabric privacy
curtains, which can be pulled fully around each bed; upholstered easy chairs where patients can sit
when out of bed; window curtaining; mattresses and bedding. All patient accommodation has heavy
duty vinyl flooring and solid plastered walls.
7.4. Hospital policies and equipment common to both wards
Before looking at the two study wards individually, the hospital policies and equipment that are
common to both wards and may have an effect on noise levels, are examined.
7.4.1. Meal times
‘Protected meal times’ are in use throughout the hospital. This means that during breakfast, lunch and
evening meal times clinical visits cease and visitors are asked to leave the ward (except family
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members if they are providing assistance with eating). This is primarily to allow the hospital staff to
monitor what is being eaten and to provide a more relaxing environment for the patients.
Each ward has a kitchen which is used for plating up hot meals and for washing up plates and cutlery
(shown in Figure 7.4). There are also fridges and a food warmer. The kitchen may be a source of
noise for patients in the opposite bay, as the kitchen door is always left open. Meals and drinks are
served to patients from a trolley, another potential source of noise.
Figure 7.4 Medical ward kitchen
Meal times are as follows:
� Breakfast is served from 08.00 to 08.30 and is followed by a tea round. Breakfast is
usually cold except for porridge
� Mid morning tea is served from 10.00 to 10.30
� Lunch is from 12.30 to 13.15, with tea served at around 13.00. Lunch is usually a hot
meal which is brought up to the ward kitchen in a heated trolley. Meals are then plated
up before being served to patients one bay at a time on a smaller trolley.
� Afternoon tea is served at 14.30
� Tea (supper) is generally a selection of sandwiches and is served from 17.30 to 18.15,
followed by a tea round at 18.00
� Drinks are available in the evening from 20.00 to 21.00
7.4.2. Ward design
At the entrance to each ward there is a ward clerk’s desk which acts as a reception area. Behind this
is a staff room and kitchen, both of which can be noisy areas. However, the bay directly opposite the
ward clerk’s desk is the only bay likely to be adversely affected by noise.
The nurse station is situated halfway down the main corridor. Potential high level noise sources here
are the nurse call, internal telephone, staff conversation and the carrying out of administrative tasks
which may affect the nearby bays and single rooms.
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7.4.3. Occupancy levels
Unlike the pilot study hospital, both these wards have a high occupancy rate throughout the entire
week, including weekends. It was therefore considered valid that noise level measurements should be
made at each location over a full seven day period, rather than the five day interval used during the
pilot study.
7.4.4. Shift patterns
Staff day shifts start at 07.00 and end at 19.30, with night shifts starting at 19.00 and ending at 07.30.
There is a half hour overlap at the beginning and end of the shifts. During this overlap there is usually
a handover session in the staff room (opposite 4-bed bay 1). Higher levels of noise may be attributed
to these changeover periods.
7.4.5. Visiting hours
These are officially 14.00 to 20.00. Attitudes amongst ward sisters vary regarding the enforcement of
these hours. Some staff consider that the positive effect on patients of visitors outweighs the other
negative aspects of having numbers of visitors on the ward out of official visiting hours.
7.4.6. Ward access
There is no ward security to prevent anyone walking on to the ward. This removes the need for a
doorbell, which could potentially be a source of noise annoyance.
7.4.7. Access to patient accommodation
All multi bed bays on the wards are open to the corridor; there are no doors. The doors of the single
patient rooms are generally left open during the day for observation purposes, but are closed at night
and during visiting times, where there is someone on hand to call a nurse if required.
7.4.8. Cleaning staff
In-house cleaning staff are used throughout the hospital rather than contractors. It is felt that this
enables more control of cleaning regimes and promotes better work ethics and loyalty. Each ward has
a dedicated cleaner who works from 07.00 until 15.00. Duties include mopping, sweeping and floor
buffing.
7.4.9. Mobile phone policy
The hospital policy specifies that mobile phones should only be used in the lobby areas and not on
the wards. This is partly to avoid disturbance and partly because mobile phones have camera and
recording capabilities which could potentially cause a breach of patient privacy or confidentiality
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7.4.10. Entertainment systems
A HTS Hospicom system is provided at each patient’s bedside. This is a pre-pay TV / radio /
telephone console. Patients are issued with headphones. A photograph of the console is shown in
Figure 7.5.
7.4.11. Rubbish bins
Quiet closing foot operated rubbish bins are in use throughout the wards. However, the opening
mechanisms are found to be quite noisy especially if the bins are placed too close to a wall or nearby
object, which then tends to be hit by the lid with some force. The body of the bins are also metal and
undamped; if a heavy object is dropped inside, this can also be a source of noise.
7.4.12. Staff call
The emergency staff call system is activated by the patient pushing a button at their bedside. This
causes a red light to flash on the ceiling outside the bay and sounds an intermittent alarm at the nurse
station. This will continue until cancelled by a member of staff.
7.4.13. Medical equipment alarms
Alarms generally sound if fluids are low or as a warning that a piece of equipment, for example a
canular, has fallen out. Mattresses used on the wards bleep if they become under-inflated.
7.4.14. Trolleys
Meals, drinks rounds, medication and dressings are all taken to the patient’s bedside on trolleys. Beds
themselves are on wheels, as is the majority of medical equipment for ease of movement. Deliveries
of fresh linens, food and other ward supplies all arrive at the ward in wheeled metal cages or on
trolleys.
7.4.15. Internal telephones
A number of internal telephones can be found on each ward, in the staff office, at the ward clerk’s
desk, the nurse station and on other staff desks in the ward corridor.
7.4.16. Hand gels
Automatic hand gel dispensers have been installed on the ward. These are motorised and work using
a sensor as shown in Figure 7.6.
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Figure 7.5 Hospicom entertainment console Figure 7.6 Automatic hand
gel dispenser
7.5. Medical ward
This ward is located on the fourth floor of the main hospital building and specialises in
Gastroenterology and care of the elderly. Elderly patients admitted to this ward are often confused
and may be suffering from a degree of dementia. Generalised medical care is also provided if the
beds are needed by patients from other specialties, for example Oncology.
Patients range in age from 18 upwards. The majority of patients have come via their GP to the AAU
(either in an ambulance or their own vehicle) and then to the medical ward following their assessment.
Patients on this ward are generally recovering from infections.
The ward has 30 beds in total, with three 6-bed bays, two 4-bed bays and 4 single rooms (an example
of which is shown in Figure 7.7). Patients are predominantly male, with one all female 4-bed bay and
single rooms used for female patients when necessary.
Figure 7.7 Single patient room
The medical ward was the first ward at Bedford Hospital to participate in the study, and before
commencement a number of issues needed to be clarified. An initial meeting was held with the ward
manager and the head of the hospital infection control team, who were shown the sound measuring
equipment. There were no undue concerns regarding the cleaning of the equipment as it would be
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located in each position for only one week. It was felt that if it did become contaminated, the
equipment case was such that it could easily be cleaned using an alcohol wipe.
Measurement locations were also discussed and possible microphone positions that would be
acceptable to the staff and patients were identified in the multi-bed bays, single rooms and at the
nurse station. For comparison purposes it was important that the microphone could be placed in
similar locations in each accommodation type, and for this to be repeatable in the surgical ward. A
ward plan showing the microphone positions can be seen in Figure 7.10 on page 99.
To minimise the risk of theft, ward staff felt that it would be sensible to hide the environmental case
containing the sound level meter either in or behind a cupboard. Given the positioning of the ward
furniture and the length of cable available (5 m), this meant that the microphone would need to be
situated close to the edge of a room, often in the corner. Due consideration was given to the possible
increase in sound pressure due to wall reflections or corner reflections. A number of tests were
carried out to investigate this, and the results can be seen in Appendix C. No significant increase in
measured level was found due to the location of the microphone close to a wall or in the corner of the
room.
To avoid the microphone being knocked or contaminated, and to be as unobtrusive as possible, it was
felt that suspending the microphone from the ceiling would be ideal. A 300 mm bracket was designed
which simply clipped around the ‘T’ shaped ceiling grid without disturbing the ceiling tiles. If the ceiling
bracket could not be used, for example in the case of a solid ceiling, the microphone was mounted on
a small tripod which was securely fastened out of reach. Figure 7.8 shows the microphone suspended
from the ceiling grid and Figure 7.9 shows the microphone and tripod positioned on a light above a
mirror in a single room.
Figure 7.8 Microphone suspended from ceiling Figure 7.9 Microphone on tripod
Questionnaires were reviewed by the ward manager and it was decided that they would be distributed
by the ward clerk to those patients who had been on the ward for over 24 hours and were felt to be fit
enough to complete the survey. Staff questionnaires were to be left for staff to complete in the staff
room.
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As with the pilot study a number of laminated advertising posters were displayed throughout the ward
common areas. These posters were aimed at both staff and patients and explained in simple terms
why and how the study was being undertaken. In addition to these posters the ward manager
personally discussed the study with all her staff during staff meetings.
7.5.1. Ward specific information
Staffing levels
The nursing staff levels are highest during the morning with seven dedicated nursing staff. This drops
to five during the afternoon and four at night. Other dedicated ward staff include a housekeeper; three
domestics; a ward clerk; an occupational therapist; and a physiotherapist.
Ward routines
The first patient visits by clinicians for general observations and the administration of intravenous
antibiotics begin at 06.00. However, activity on the ward does not begin fully until 07.30, when the
main lights are switched on.
Two ward rounds begin at 09.00 (Monday and Friday), with two consultants from different specialities:
‘Care of the Elderly’ and ‘Gastroenterology’. As well as the consultant ward rounds, the junior doctors
work in the ward throughout the day talking to patients, checking bloods and organising discharges. In
addition to the doctors ward rounds, bloods are also taken by the phlebotomists at 09.00-09.30 and
18.00-19.00.
The ward lights are dimmed after 21.00.
Sources of noise specific to the medical ward
Patients who are suffering from dementia are given a wrist tag which causes an alarm to sound if the
patient tries to leave the ward.
There is a pneumatic system for the distribution of pharmaceuticals close to the nurse station and a 6-
bed bay.
Figure 7.10 Detailed plan of the medical ward showing microphone positions
Pneumatic system
Microphone position
Sink
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7.6. Medical ward overall noise survey results
Noise level measurements were made at eight different locations on the medical ward. Table 7.1
shows the locations, measurement periods and the patient genders where applicable.
Table 7.1 Medical ward - measurement locations, time periods and patient gender
Position Length of measurement period Patient gender
Ward entrance 7 days N/A
Nurse station 7 days N/A
4-bed bay 1 12 days Male
4-bed bay 2 7 days Male
6-bed bay 3 6 days Male
6-bed bay 4 8 days Male
Single room A 5.5 days M/F
Single room B 7 days M/F
The results reported for bay 1 are those made after the ceiling tiles were changed for those with better
acoustic properties, as discussed in Chapter 8. This ensured that reported results were comparable
with the other bays on the ward with similar ceiling tiles.
Overall measurements of A-weighted equivalent sound pressure levels (LAeq) for 24 hours, night and
day time were recorded at each location and are shown in Table 7.2.
Table 7.2 Average LAeq measured for 24 hour, day and night time periods at each location
Position in ward Average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Ward entrance 53.7 55.2 46.4
Nurse station 54.0 54.9 50.0
4-bed bay 1 49.4 51.3 41.8
4-bed bay 2 49.8 51.1 44.1
6-bed bay 3 54.0 55.2 50.1
6-bed bay 4 49.7 51.2 42.4
Single room A 59.3 60.6 51.1
Single room B 52.6 53.9 47.3
A summary of the day and night time average levels presented in Table 7.2 are shown graphically in
Figure 7.11 for clarity. As with the pilot study ward, all levels in patient accommodation exceed those
suggested in the WHO guidelines without exception. It can be seen that day time levels measured at
the ward entrance and the nurse station are similar, as are the day time levels in bays 1, 2 and 4.
However, levels in bay 3 and the single rooms are less consistent. The drop between day and night
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time levels varies from 9.5 dB in bay 1, to only 5 dB in bay 3 and at the nurse station. Possible
reasons for these differences are discussed in Section 7.6.4.
0
5
10
15
20
25
30
35
40
45
50
55
60
65
Ward entrance Nurse station 4-bed bay 1 4-bed bay 2 6-bed bay 3 6-bed bay 4 Single room A Single room B
Sou
nd
Pre
ssu
re (
dB
LA
eq
,1h
r)
Day time LAeq, 16hr
Night time LAeq, 8hr
Figure 7.11 Average day and night LAeq levels measured at each location
The following sections examine the noise levels recorded at different locations on the ward in further
detail.
7.6.1. Nurse station and ward entrance
Figure 7.12, shows the average measured LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station
and the ward entrance by the ward clerk’s desk. It can be seen that noise levels in both locations
increase steadily from around 04.30am, and at the nurse station, levels do not decrease substantially
until around 01.00. The levels at the ward entrance decrease earlier than at the nurse station and
remain consistently lower during the night. This is as one would expect given the nurse station is
staffed 24 hours a day, whereas the ward clerk is only at the desk during day time office hours, and
then the desk is only used periodically by other staff. However noise levels at the ward entrance are
also affected by activity in the staff room and kitchen which are situated directly behind the ward
clerk’s desk area, as can be seen in the ward plan shown in Figure 7.10 on page 99.
The measured LA90,1hr levels provide a good indication of the variation in background noise levels over
time. Night time background levels reduce from around 38 dB LA90 to around 34 dB LA90 during the
quietest period, while day time background levels are fairly steady at around 42 dB LA90. Background
levels at the ward entrance exceed those at the nurse station twice during the day: first around the
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time of the morning shift handover, breakfast and start of the morning ward rounds; and secondly
during lunch time, when hot meals are plated up in the kitchen.
20
30
40
50
60
70S
ou
nd
Pre
ssu
re (
dB
A)
Time (24h:00)
Nurse Station LAeq Ward entrance LAeq Nurse Station LA90 Ward entrance LA90
Night time
Day time
Figure 7.12 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station and ward entrance
Viewing averaged noise levels over time, as in Figure 7.12 above, provides valuable information with
regards to level consistency and overall day and night time variation patterns, but does not illustrate
the fluctuating nature of noise in the short term. Figure 7.13 shows noise levels captured at the nurse
station over a ten minute time interval with the microphone approximately 2 m away from the main
desk area. Using the trigger files captured when LAmax exceeds 70 dB, certain high level noise events
have been identified.
Figure 7.13 LAmax,2s and LAeq,2s fluctuating over a ten minute interval at the nurse station
FURNITURE
SCRAPING
ON FLOOR
INTERMITENT
NURSE CALL LAmax,2s
LAeq,2s
CLOSING
ROOM DOORS
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The events shown in Figure 7.13 are a good representation of the types of high level noise events
recorded at the nurse station. Furniture scraping is found to be a constant source of high level noise
which could be simply and cheaply controlled by fitting rubber feet or wheels to the chairs used. Doors
are also a problem, with doors to two single rooms situated at the back of the nurse station and a set
of large metal storage cupboards to one side. These often cause high levels of noise on closing.
Again this could be easily and cheaply rectified.
To further illustrate the types and noise levels of typical high level events at the nurse station,
examples are presented in Table 7.3. It should be noted that the levels shown are for individual
events and may not be representative of every noise event of that type.
Table 7.3 Examples of noise events at the nurse station
Noise event LAmax (dB)
Nurse call 72.8
Door banging 77.3
Furniture scraping on floor 85.6
Metal cupboard door 84.3
Internal phone 71.6
Rubbish bin 78.7
7.6.2. Multi-bed bays
Figure 7.14 shows the averaged LAeq,1hr levels measured over 24 hours for two six bed and two four
bed bays. It can be clearly seen that levels for bays 1, 2 and 4 are very similar and follow the same
general pattern of fluctuation. This suggests firstly that an increase in ward size from four to six
patients does not necessarily affect the noise levels, and secondly that the daily ward routines which
contribute to the noise levels are comparable. The levels in bay 3, however, are consistently higher
than those in the other bays, by 4 dB LAeq on average during the day and by up to 8 dB LAeq during the
night. This particular bay is opposite the nurse station, and for observation purposes the patients with
the most serious conditions are placed here. Due to the type of patients on this ward, the main impact
on the noise levels is both from the patients themselves, for example, crying out, coughing and
groaning and the increased clinical activity in the bay. Unlike bays 1, 2 and 4, bay 3 has a solid
plaster ceiling rather than a suspended ceiling with acoustic tiles. This may also have a negative
impact on noise level.
Figure 7.14 also shows that the WHO day / night division is not a particularly good fit. Noise levels
increase steadily from around 05.30 rather than 07.00, and begin to decrease after the evening meal
is served and then further decrease at 23.00. This suggests it might be appropriate to redefine the
‘day’ and ‘night’ time periods for hospital noise assessment.
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20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Medical 4-Bed Bay 1 Medical 4-Bed Bay 2 Medical 6-Bed Bay 3 Medical 6-Bed Bay 4
Night time Day time
WHO GUIDELINES
Figure 7.14 Average LAeq,1hr levels over 24 hours for the multi-bed bays
Background levels, in terms of LA90, are shown in Figure 7.15. Levels in bays 1, 2 and 4 have been
averaged for purposes of clarity and it can be seen that background levels in these bays are around
39 dB LA90 during the day and 32 dB LA90 at night. Bay 3 has considerably higher background levels of
around 46 dB LA90 during the day and 41 dB LA90 at night, higher than those at the nurse station
opposite (see Figure 7.12).
20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Mean LA90 Bays 1,2,4 Mean LA90 Bay 3
Night time Day time
Figure 7.15 Average LA90,1hr levels over 24 hours for the multi-bed bays
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7.6.3. Single patient rooms
Figure 7.16 shows the average LAeq,1hr levels over 24 hours in the two single rooms measured. The
levels measured in the multi-bed bays have been averaged, and the average is also shown on the
graph to allow for comparison between single rooms and multi-bed bays.
It can be seen that levels for single room B are similar to those of the multi-bed bays, but noise levels
measured in single room A are considerably higher. Much of this high level noise was caused by visits
to the patient by groups of relations who would arrive around 14.00 and often stay until 21.00. During
this time conversation was constant. Noise levels were also impacted by the patient’s condition and a
lack of cooperation with members of the nursing staff. Consideration should also be given to the fact
that room A has a solid plaster ceiling rather than a suspended ceiling with acoustic tiles. This may
also have had a negative impact on noise levels.
20
30
40
50
60
70
So
un
d P
res
su
re (d
B L
Aeq
,1h
r)
Time (24h:00)
Medical ward - single room A Medical ward - single room B Average of multi bed bays
Night time Day time
WHO GUIDELINES
Figure 7.16 Average LAeq,1hr levels over 24 hours for the single rooms
Figure 7.17 shows the LAmax,2s and LAeq,2s between 14.00 and 17.00 in single room A and illustrates
the impact of visiting time on the noise levels. Average noise levels during this period increase to 66
dB LAeq, with an occurrence of 89.3 dB LAmax.
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Figure 7.17 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a three hour period
in single room A
7.6.4. Further analysis of high level noise sources
To help build up a further picture of the sources of high level noise at each location, the numbers of
occurrences of LAmax in 5 dB bands from 70 to 95 dB have been examined. Figures 7.18 and 7.19
show the average number of high level noise events per day and per night in different measurement
locations.
0
50
100
150
200
250
300
350
400
450
500
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
90 ≤ LAmax < 95 dB
Figure 7.18 Average number of high level noise events recorded at each location per day
VISITING TIME
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It can be seen that the numbers of high level noise events in single room A during the day exceed
those in all other locations, with on average, over 450 events with LAmax between 70 and 75 dB; over
250 events with LAmax between 75 and 80; and over 100 events with LAmax above 80 dB. As discussed
in the previous section, the majority of these high level events are due to loud conversation during
visiting time, which raises the following question: If this patient had been in a multi-bed bay, would the
visitors have felt more inclined to speak more quietly? The ward manager in this medical ward has a
positive view on the benefits of visiting time, and does not strictly enforce visiting hours. However, are
these long periods of loud conversation actually beneficial to the patient? Would these lengthy visits
have been curtailed if this had been a daily occurrence in a multi-bed bay?
Although, as discussed in Section 7.6.2, overall noise levels in bays 1, 2 and 4 are shown to be
similar, differences can be seen between the bays in terms of the average numbers of high level
noise events. Bay 1 is opposite the ward clerk’s desk, kitchen and staff room and is shown to have on
average over 50 more high level noise events during the day than the next bay along the corridor.
This is thought to be due to noise from the ward clerk’s desk area, kitchen and staff room and this is
further confirmed by patient comments in the questionnaire surveys, as discussed in Section 7.11.
Day and night time average noise levels for bay 3 and the nurse station which is opposite are very
similar, as are the numbers of high level noise events. However, by looking at the overall noise levels
it is unclear whether any of the activities at the nurse station have an adverse effect on noise levels in
the opposite bay or whether they are unrelated. Further investigation appears to suggest that as first
thought; the majority of sources of high level noise in bay 3 appear to be linked to increased clinical
activity and patients’ conditions and behaviour. The nurse call appears to be the only nurse station
related activity which is recorded at comparable levels in bay 3.
Figure 7.19 shows a very different pattern of occurrences of high level noise events during the night. In
this case it is the nurse station and bay 3 which show the highest numbers of events. This is
unsurprising as the nurse station is manned for 24 hours a day, and bay 3 is used for more seriously ill
patients who require constant care. Sources of high level noise at the nurse station are the nurse call,
furniture scraping on the floor, doors banging and administrative tasks, while patients’ crying out and
clinical activity are typical of high level noise events in bay 3.
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0
10
20
30
40
50
60
70
80
90
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 7.19 Average number of high level noise events recorded at each location per night
For illustration purposes, typical sources of high level noise recorded in the bays and single rooms are
shown in Table 7.4, together with their noise level (LAmax). It should be noted that the exact position of
the noise source relative to the microphone is unknown. Where human activity is measured it can be
reasonably assumed that this has occurred at the closest bed to the microphone (approximately 2 m in
distance).
Table 7.4 Examples of noise sources and levels on the medical ward
Noise event LAmax (dB)
Trolleys (various) 77.7; 84.8
Checking patient's notes at the bedside (ring binder) 83.6
Patient snoring 70.4
Patient's mobile phone ringing 75.4
Cough 79.4
Loud crash (measured in bay 1) 80.9
Medical equipment alarm 72.5
Noisy motorbikes (measured in single room with window open) 72.5
Sirens (unknown if window open or closed) 74.0
Rubbish bin 76.5
Changing bin bag 92.7
Crash from kitchen (measured in bay 1) 94.5
Dropped object in corridor (measured in bay 1) 103.1
Nurse call (measured in bay 3) 72.5
Sneeze 89.4
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It can be seen in Table 7.4 that several noise events are measured at over 90 dB LAmax, with a
dropped object generating a level of 103.1 dB LAmax. Such high noise levels would undoubtedly cause
annoyance and disturbance to patients and staff nearby.
7.7. Surgical ward
This ward is located on the 3rd
floor of the main hospital building, directly under the medical ward, and
is for elective orthopaedic procedures. This includes surgery to joints, hands, arms, shoulders and
breast surgery. Patients range in age from 18+ and length of stay ranges from less than 24 hours to
up to around 10 days.
The ward has 26 beds in total, with four 4-bed bays, a 6-bed bay and 4 single rooms. Bays are
predominantly female, with one all male 4-bed bay and single rooms used for male patients when
necessary.
With the equipment already sanctioned by the infection control team, only microphone positions and
questionnaire distribution needed to be discussed with the ward manager, who was extremely
supportive of the study. For comparison purposes it was suggested that similar microphone positions
should be used to those in the medical ward. The ward manager was happy for this to be the case,
and a ward plan indicating these positions can be seen in Figure 7.20 on page 111. As in the medical
ward, the microphone was suspended from the ceiling where possible.
Questionnaires were also reviewed by the ward manager and it was decided that they would be
distributed by the ward clerk to those patients who had been on the ward for over 24 hours and were
felt to be fit enough to complete the survey. Staff questionnaires were to be left for staff to complete in
the staff room.
As in the medical ward a number of laminated advertising posters were displayed throughout the ward
common areas.
7.7.1. Ward specific information
Staffing levels
The nursing staff levels are highest during the morning with five dedicated nursing staff. This drops to
four during the afternoon and three at night. Other dedicated ward staff include a housekeeper; three
domestics, ward clerk; dedicated occupational therapist; and a physiotherapist.
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Ward routine
Observation rounds begin at 06.00, with drug rounds and first admissions beginning an hour later.
Doctors and anaesthetists arrive for morning admissions around 08.30 and may be on the ward for
several hours. Porters begin to take patients to the operating theatre at this time.
In the late morning, staff begin to take their breaks and patient discharges are discussed, causing
more activity around the nurse station. Physiotherapists & occupational therapists carry out their
duties on the ward; drug rounds continue; porters are busy taking patients for X-rays and bringing
back patients from surgery.
From 13.30 until 14.00 there is a shift handover which takes place both in the office and at the
bedside. Sometimes this can lead to five or six people gathered around a patient’s bed, which can
generate some noise.
The second round of admissions arrive at 14.00; observations of patients back from surgery continue;
bloods and x-rays are taken in preparation for surgery; doctors arrive on the ward to visit new
admissions.
At 16.00 staff begin to take breaks and at 17.30 day surgery patients begin to go home. Drug rounds
are ongoing.
Sources of noise specific to the surgical ward
The following are potential sources of noise on the ward:
� The defibrillator self tests at 03.00
� A series of bleeps from the fire alarms can be heard down the corridor – possibly a self test?
� The fire exit door at the end of the ward is heavy and is ill-fitting in its frame. Although it is
fitted with a quiet closer it vibrates loudly on closing.
� The cupboard, which is opposite 4-bed bay 4, has a noisy metal roller shutter.
Figure 7.20 Detailed plan of the surgical ward showing microphone positions
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7.8. Surgical ward overall noise survey results
Noise level measurements were made at six different locations on the surgical ward. Table 7.5 shows
the locations, measurement intervals, and the patient genders where applicable.
Table 7.5 Measurement location, time periods and patient gender type
Position Length of measurement period Patient Gender
Nurse station 7 days N/A
4-bed bay 1 6 days Male
6-bed bay 3 8 days Female
4-bed bay 4 7 days Female
Single room A 7 days Male / Female
Single room B 7 days Male / Female
Overall measurements of A-weighted equivalent sound pressure levels (LAeq) for 24 hours, night and
day time were recorded at each location and are shown in Table 7.6.
Table 7.6 Average LAeq for 24 hour, day and night time periods at each location
Position in ward Average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Nurse station 54.5 55.8 48.6
4-bed bay 1 51.7 53.1 41.4
6-bed bay 3 51.0 53.6 41.8
4-bed bay 4 50.9 52.6 42.0
Single room A 55.1 56.8 44.6
Single room B 56.5 58.2 46.4
A summary of the day and night time average levels presented in Table 7.6 are presented graphically
in Figure 7.21 for clarity. As with the medical ward, all levels in patient accommodation exceed those
suggested in the WHO guidelines without exception. It can be seen that day time and night time levels
measured in bays 1, 3 and 4 are very similar with an average night time drop of 11 dB. As found in
the medical ward, single patient rooms are less consistent both during the day and night.
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0
5
10
15
20
25
30
35
40
45
50
55
60
65
Nurse station 4-bed bay 1 6-bed bay 3 4-bed bay 4 Single room A Single room B
Sou
nd
Pre
ssu
re (
dB
A)
Day time LAeq, 16hr
Night time LAeq, 8hr
Figure 7.21 Average day and night LAeq levels measured at each location
Detailed results of levels measured at the nurse station are discussed in the next section, with further
results from the multi-bed bays shown in Section 7.8.2 and from the single rooms in Section 7.8.3.
7.8.1. Nurse station
Figure 7.22 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station.
20
30
40
50
60
70
So
un
d P
res
su
re (d
B L
Aeq
,1h
r)
Time (24h:00)
Nurse Station LAeq Nurse Station LA90
Night time
Day time
Figure 7.22 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station
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As with the nurse station in the medical ward, noise levels increase steadily from around 04.30 and do
not decrease substantially until late, around 23.30. Night time background levels are very consistent
at around 30 dB LA90, while day time background levels are around 40 dB LA90, with a temporary peak
at around 14.00 during the afternoon shift handover and the second round of patient admissions.
Levels begin to decrease from around 19.30.
Sources of high level noise seem to differ slightly from those captured at the nurse station in the
medical ward. Here, analysis of the trigger files indicates that the nurse call was used much more
frequently. This was confirmed by staff and patient responses to the questionnaire surveys, discussed
in Sections 7.9.1 and 7.9.2 respectively. High level conversation was also the source of many trigger
files, but unlike the medical ward high level noise due to furniture scraping on the floor was minimal.
Administrative tasks involving the use of ring binders also created a number of trigger files especially
during the night. This is further illustrated in Figure 7.23, which shows a number of peaks caused by
the closing of ring binders over a 30 minute period.
Figure 7.23 LAmax,2s (green trace) and LAeq,2s (red trace) measured over a thirty minute interval
during the night, from 2.40am, at the nurse station
Figure 7.24 shows an example of the nurse call captured with the microphone approximately 2 m
away from the main desk area. In this particular instance the nurse call was activated for over eight
minutes before it was reset. Each intermittent tone measured 70.4 dB LAmax, with an overall LAeq of
59.5 dB.
RING BINDER
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Figure 7.24 LAmax,2s and LAeq,2s fluctuating over a 11 minute interval at the nurse station
Further examples of high level noise levels captured at the nurse station, are presented in Table 7.7
below. It should be noted that the levels shown are the levels of individual events and so may not be
representative of every noise of that type.
Table 7.7 Examples of noise events at the nurse station
Noise event LAmax (dB)
Nurse call 70.4; 72.7
Internal phone 76.8
Ring binder 82.6
Door banging further down ward corridor 70.6
It can be seen in Table 7.7 that the closing of a ring binder generates noise at levels as high as 82.6
dB LAmax. As much of the administrative work is carried out by staff during the night when the ambient
noise level on the ward is low, this activity is likely to cause disturbance to those patients in the bay
opposite the nurse station.
7.8.2. Multi-bed bays
Figure 7.25 shows the averaged LAeq,1hr levels over 24 hours for one 6-bed and two 4-bed bays and
the average background level (LA90,1hr) of all bays. It can be clearly seen that levels for the measured
bays are very similar and follow the same general pattern of fluctuation, with night time levels falling to
around 37 dB LAeq, and day time level remaining steady at around 53 dB LAeq. The average
background level varies from around 32 dB LA90 at night to around 40 dB LA90 during the day, similar to
three of the multi-bed bays in the medical ward.
INTERMITENT
NURSE CALL LAmax,2s
LAeq,2s
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Figure 7.25 also shows that, as in the medical ward, the WHO day / night division is not a particularly
good fit. Noise levels increase steadily from around 05.30 rather than 07.00, and begin to decrease
after the evening meal is served and then further decrease at 23.00. This suggests it might be
appropriate to redefine the ‘day’ and ‘night’ time periods for hospital noise assessment and perhaps
consider the addition of an ‘evening’ period.
The similarity of the measured levels between the 4-bed and 6-bed bays suggest, as with the medical
ward, that an increase in ward size from four to six patients does not necessarily affect the noise
levels. The consistency of the levels indicates that the daily ward routines which contribute to the
noise levels are comparable.
20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
4-Bed Bay 1 6-Bed Bay 3 4-Bed Bay 4 Average LA90
Night time Day time
WHO GUIDELINES
Figure 7.25 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level for all bays
over 24 hours
7.8.3. Single patient rooms
Noise levels were measured in two single rooms. Figure 7.26 shows the average measured LAeq,1hr
levels over 24 hours and the average background level (LA90,1hr) of both rooms. To allow for
comparison with levels measured in the multi-bed bays, the average LAeq,1hr and the average
background level (LA90,1hr) of all the multi-bed bays are also shown on the graph.
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20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Single room A LAeq Single room B LAeq Multi-bed bay average Average LA90 - Single Rooms Average LA90 - Multi-bed bays
Night time Day time
WHO GUIDELINES
Figure 7.26 Average LAeq and LA90 levels for single rooms A and B and multi-bed bays
It can be seen that, as in the medical ward, noise levels measured in both single rooms are consistent
higher than those measured in the multi-bed bays. Background levels (LA90,1hr) are also higher, with
levels around 2 dB higher at night and as much as 4 dB higher during the day.
The patient in single room B had been on the ward for some weeks and seemed to enjoy chatting to
staff and her numerous visitors. As well as noise generated as a result of her clinical care, much of
the high level noise in this room was caused by conversation. This was particularly noticeable
between 15.00 and 20.00, where it can be seen in Figure 7.26 that noise levels consistently exceed
those measured in single room A. This is due to high levels of conversation during visiting time.
In single room A conversation was again responsible for a percentage of high level noise, but medical
equipment alarms also had an impact in this room. One particular type of alarm often generated high
level noise with its intermittent 30 second bleep. An occurrence of this was found to continue for over
two hours and a half hours before it was reset, with each bleep measuring close to 75 dB LAmax . The
effect of this is further illustrated in Figure 7.27.
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Figure 7.27 LAmax,2s (green trace) and LAeq,2s (red trace) showing the noise levels due to a medical
equipment alarm over a 13 minute period
Single room A is situated directly behind the nurse station. As discussed previously, doors to the
single rooms are generally left open to allow for easy observation of the patient. Staff talking, the
nurse call and internal phone ringing can all be heard clearly in the background from this bay, with the
nurse call measured at levels around 67 dB LAmax, and the internal phone measured at levels around
53 dB LAmax..
7.8.4. Further analysis of high level noise sources
To help build up a further picture of the sources of high level noise at each location, the numbers of
occurrences of LAmax in 5 dB bands from 70 to 95 dB have been examined. Figures 7.28 and 7.29
show the average number of high level noise events during the day and night in different
measurement locations.
It can be seen that the numbers of high level noise events in single room A during the day exceed
those in all other locations, with, on average, almost 500 events with LAmax between 70 and 75 dB;
around 150 events with LAmax between 75 and 80; and 30 events with LAmax above 80 dB. As
discussed in the previous section, these high level events are partly due to conversation with staff and
visitors, but are also impacted to a large extent by a particular piece of medical equipment with a high
pitched alarm. Alarms generally sound when equipment requires some kind of attention, for example
fluid levels are becoming low. Staff are obviously aware of the length of time they have before they
need to respond to an alarm; however, in this case one occurrence of this high pitched intermittent
bleep was observed to continue for over two and a half hours. This must have been annoying to the
patient, who was trying to rest after an undergoing an operation on the previous day. Perhaps if this
alarm had been in a multi-bed bay it may have been attended to sooner, especially if other patients
were annoyed by the noise and alerted staff.
INTERMITTENT BLEEP
OF MEDICAL
EQUIPMENT ALARM
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The differences in numbers of high level noise events between locations emphasise the limitations of
using only LAeq levels to describe the noise climate of hospital wards. In terms of LAeq,1hr room B has
higher levels (see Table 7.6 and Figure 7.26) yet in terms of individual high noise events Figure 7.28
shows that room A is ‘noisier’.
0
50
100
150
200
250
300
350
400
450
500
4-Bed Bay 1 6-Bed Bay 3 6-Bed Bay 4 Single room A Single room B Nurse Station
Nu
mb
er
of
hig
h l
ev
el n
ois
e e
ve
nts
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
90 ≤ LAmax < 95 dB
Figure 7.28 Average number of high level noise events captured at each location per day
Many high level noise events can also be seen in single room B, with over 400 events with LAmax
between 70 and 75 dB; over 200 events with LAmax between 75 and 80; and around 80 events with
LAmax above 80 dB. When first admitted onto the ward, the patient in this room had been put in a multi-
bed bay. Here she had enjoyed talking to fellow patients and was disappointed when she was moved
into a single room, feeling more cut-off. This lady took every opportunity to chat with staff and visitors
for company which caused the majority of the high level noise events.
Although, as discussed in Section 7.8.2, overall noise levels in bays 1, 3 and 4 are shown to be
similar, differences can be seen between the bays in the numbers of high level noise events. As in the
medical ward, bay 1 is opposite the ward clerk’s desk, kitchen and staff room. Noise events from
these areas have been shown to impact the noise environment of this bay; this is further confirmed by
patient responses to questionnaire surveys, discussed in Section 7.11.
Unlike the medical ward the numbers of high level noise events captured in bay 3, which is opposite
the nurse station, were the lowest. This further confirms the fact that noise from the nurse station is
having a minimal impact on the noise levels in this bay.
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More sources of high level noise were captured at the nurse station on the surgical ward. As
discussed in Section 7.8.1 many of these were due to conversation. The nurse call also appeared to
be used more in this ward. The surgical ward is very different to the medical ward in terms of timings,
logistics and planning of operations. It is unsurprising to find more discussion at this nurse station as
the general pace of this ward is more frenetic than that of the medical ward.
0
10
20
30
40
50
60
70
80
90
100
110
4-Bed Bay 1 6-Bed Bay 3 6-Bed Bay 4 Single room A Single room B Nurse Station
Nu
mb
er
of
hig
h l
ev
el n
ois
e e
ve
nts
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 7.29 Average number of high level noise events captured at each location per night
Figure 7.29 shows that the numbers of high level noise events during the night are generally much
lower than those observed in the medical ward. This is mainly due to the differences in the numbers
of instances of patients crying out, which was very noticeable in the medical ward. This is further
confirmed by patient responses to questionnaire surveys, discussed in Section 7.9.2.
7.9. Results of the staff questionnaire surveys
Staff response was good in the medical ward with 18 questionnaires completed, but response in the
surgical ward was rather poor, with only seven staff completing the survey. The following section
discusses results from the staff questionnaires and examines the differences between perceptions on
the medical and surgical wards.
Information regarding the design of the questionnaire surveys can be found in Section 5.4.
7.9.1. Staff profile
To establish certain attributes about the staff, the first section posed a number of basic questions. Out
of the 18 respondents on the medical ward only two were male, and all seven respondents in the
surgical ward were female.
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The ages of the respondents in the two wards are shown in Figure 7.30. It can be seen that in both
wards the respondents are generally younger than 50, with a higher percentage of young staff
members completing the questionnaire in the medical ward.
0
5
10
15
20
25
30
35
40
45
50
20 - 30 31 - 40 41 - 50 51 - 60 60+
Pe
rce
nta
ge
of
resp
on
de
nts
(%
)
Age band (years)
Medical
Surgical
Figure 7.30 Age of respondents by band
Questions were asked in relation to the length of time worked both on the ward and at the hospital,
and the responses can be seen in Figures 7.31 and 7.32 respectively. What is clear is that staff
turnover in the surgical ward appears to be relatively low, with nearly 60% of respondents having
worked on the ward for over five years. The medical ward was more mixed, with an influx of new staff
(~40%) in the last year. It also appears some staff had transferred from other wards within the hospital
during their career.
0
10
20
30
40
50
60
Less than
1 year
1 - 2
years
2 - 3
years
3 - 4
years
4 - 5
years
5+ years
Pe
rce
nta
ge
of
resp
on
de
nts
(%
)
Time worked on the ward
Medical
Surgical
0
10
20
30
40
50
60
70
80
Less than
1 year
1 - 2
years
2 - 3
years
3 - 4
years
4 - 5
years
5+ years
Pe
rce
nta
ge
of
resp
on
de
nts
(%
)
Time worked on the hospital
Medical
Surgical
Figure 7.31 Time worked on the ward Figure 7.32 Time worked at the hospital
7.9.2. Noise annoyance
General feelings of noise annoyance were investigated by asking staff to what extent they were
annoyed by noise. Figure 7.33 shows that the highest percentage of staff in the medical ward were
moderately annoyed by noise (43%), but this was not the case in the surgical ward, where the
majority (56%) of those questioned felt only slightly annoyed by noise.
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0 10 20 30 40 50 60
Not at all
Slightly
Moderately
Very much
Extremely
Percentage (%)
Surgical
Medical
Figure 7.33 Staff perception of noise in terms of annoyance
Staff were asked to rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating
‘not at all annoying’ and 4 indicating ‘a great deal’. Figure 7.34 shows the percentages of staff who
rated a noise event with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the
event.
It can be seen that the most annoying noise events for the staff on the medical ward were visiting
time, medical equipment alarms and the internal telephone. This is similar for the surgical ward,
except that there the nurse call is also rated by a high percentage of respondents.
Discrepancies of between 20% and 30% can be seen between the medical and surgical ratings for
cleaning, people talking and staff talking. These events were found to be annoying by staff on the
medical ward, but to a much lesser extent in the surgical ward.
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0 10 20 30 40 50 60 70 80 90 100
External noise
TV / radio
Doors banging
Footsteps
Staff talking on the telephone
Mobile phones ringing
Trolleys
Meal times
Talking on mobile phones
Nurse call
Rubbish bins
People talking
Cleaning
Internal telephone
Medical Equipment
Visiting time
% of staff rating annoyance event 2 or above
Surgical (n=7)
Medical (n=18)
Figure 7.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4
Doors banging and external noise are rated more highly in the surgical ward. There is a particular
heavy, ill-fitting fire door at the end of this ward that was mentioned during initial discussions with the
ward manager. When this door bangs shut the noise appears to travel down the full length of the ward
corridor. With regards to the external noise; the surgical ward was surveyed during the summer
months when the weather was warmer, whereas the medical ward was surveyed in the spring. This
may account for the difference in external noise annoyance, as more windows may have been open
in the warmer weather.
For 10 out of 16 noise sources, the percentages of those annoyed on the surgical ward are higher
than on the medical ward. This could of course be simply down to the smaller sample size, and the
possibility that only those staff who felt strongly about noise felt inclined to complete the
questionnaire. However, other factors could also account for this difference. Medical and surgical
wards are different, and as such may attract staff with certain personalities. Surgical wards are very
busy with constant admissions for day or even half day procedures. Operations are booked in
advance and efficiency and timing are key. Medical wards are slower paced and it is possible that
staff annoyance of particular events could be less extreme.
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7.9.3. Interference with work
Respondents were asked to what extent noise interfered with their ability to work effectively. As can
be seen in Figure 7.35, opinions of the respondents in the surgical ward were very split, whereas the
majority of medical ward staff chose ‘slightly’ or ‘not at all’.
0 10 20 30 40 50
Not at all
Slightly
Moderately
Very much
Extremely
Percentage (%)
Surgical
Medical
Figure 7.35 Staff perception of the extent to which noise interferes with work
Staff were also asked to rate how much each noise event interfered with their ability to carry out their
job effectively (again the rating scale of 0 to 4 was used). Figure 7.36 shows the percentages of staff
who rated a noise event with a 2, 3 or 4, and as such it could be said that this noise event interfered
to some extent with their ability to carry out their job effectively.
0 10 20 30 40 50 60 70 80 90 100
External noise
Meal times
Doors banging
Footsteps
Cleaning
TV / radio
Mobile phones ringing
People talking
Rubbish bins
Trolleys
Talking on mobile phones
Nurse call
Staff talking on the telephone
Internal telephone
Medical Equipment
Visiting time
% of staff rating interference event 2 or above
Surgical (n=7)
Medical (n=18)
Figure 7.36 The percentages of staff rating an interference noise event with a 2, 3 or 4
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As with the noise annoyance ratings, visiting time, medical equipment alarms and the internal
telephone were all rated as interfering with work by over 40% of respondents in each ward.
There are several anomalies worth noting. The nurse call is once again rated by a high percentage of
surgical staff as well as the trolleys and meal times; however these are not rated by a high percentage
of medical staff. Trolleys are used in both wards a great deal, but in the surgical ward patients are
often being wheeled through the ward to and from surgery and X-ray so trolley noise may be more
disruptive. It is unclear why meal times would be more disruptive in the surgical ward.
7.9.4. Important sounds
To aid understanding of which sounds were felt by staff to be important to be heard in order to carry
out their jobs effectively, staff were asked to rate different noise events on a scale of 0 to 4, where 0
indicated ‘not at all important’ and 4 indicated ‘extremely important’.
Figure 7.37 shows the mean ratings for each noise event. It can be seen that ‘conversations with
colleagues’ closely followed by ‘conversations with patients’ were considered by staff in both wards to
be the most important noise events. However, the average ratings were consistently high in all cases
suggesting that all of these events are important for staff. As with the annoyance and interference
ratings in the previous sections, staff in the surgical ward rated most events as more important than
those in the medical ward, but a similar pattern can be seen.
0
1
2
3
4
Nurse call Conversations
with colleagues
Conversations
with patients
Medical
equipment
alarms
Patients calling
out
Patient activity
Surgical (n=7)
Medical (n=18)
Figure 7.37 Mean importance rating of certain noise events
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7.10. Results of the patient questionnaire surveys
With the help of the ward clerks, questionnaires were distributed to those patients who had been on
the ward for over 24 hours and were judged to be physically and mentally fit enough to complete the
survey. In total 40 patients completed the questionnaire in the medical ward and 42 in the surgical
ward.
The following sections discuss results from the patient questionnaires and examine the differences
between perceptions on the medical and surgical wards.
7.10.1. Patient profiles
As with the staff questionnaire, the first section aimed to establish certain attributes about the
patients, beginning with gender. As discussed previously, the surgical ward was predominantly
female, and the medical ward predominantly male. This is shown clearly in Figure 7.38 below.
0
10
20
30
40
50
60
70
80
90
Male Female
Pe
rce
nta
ge
(%
)
Medical ward (n=40)
Surgical ward (n=42)
Figure 7.38 Gender split by ward type
Figure 7.39 shows the respondents’ age ranges. It can be seen that a relatively high percentage of
patients were aged 60 or above, with 70% in the surgical ward and 40% in the medical ward in this
age range.
0
10
20
30
40
50
60
70
80
20-30 31-40 41-50 51-60 60+
Pe
rce
nta
ge
(%
)
Age range
Medical ward (n=40)
Surgical ward (n=42)
Figure 7.39 Patients age by band
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Patients were asked how long they had been on the ward. Some differences can be seen between
the surgical ward and medical ward in Figure 7.40 below. Nearly 80% of respondents in surgical were
short term patients, having been on the ward for less than one week. It can be seen that the variation
in the medical ward was more marked.
0
10
20
30
40
50
60
70
80
90
< 1 week 1- 2 weeks 2 - 3 weeks 3+ weeks
Pe
rce
nta
ge
(%
)
Length of stay
Medical ward (n=40)
Surgical ward (n=42)
Figure 7.40 Length of patient stay when completing the questionnaire
Hearing impairment was also explored, with 24% of respondents on the medical ward and 17% on the
surgical ward indicating that they did suffer to some degree
The bed number of the respondent was noted on the front of the questionnaire by the ward clerk. This
number provided useful location information which is considered when investigating relationships
between bed positioning and patient accommodation type with day time noise annoyance and night
time disturbance, which are explored in Chapter 11. In terms of the single room / multi bed bay split,
91% of respondents in the medical ward were in multi-bed bays, with 83% in the surgical ward.
7.10.2. Noise annoyance and disturbance
The next section of the questionnaire considered day time noise annoyance and night time
disturbance. The questionnaire sought to identify the sources of noise that may annoy or disturb
patients. Respondents were given two lists of noises and were asked to rate the day time annoyance
and night time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4
indicated a great deal). Several lines were left blank at the bottom of the lists for patients to add and
rate additional noise sources.
Patients were first asked how they perceived the day time noise environment on the ward. Figure 7.41
details the responses, which are fairly split between ‘quiet’ and ‘a little noisy’. Interestingly, when
asked whether they were actually annoyed by noise, only 13% of patients in the medical ward felt
annoyed, and 29% of patients on the surgical ward.
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0 10 20 30 40 50 60
Very quiet
Quiet
A little noisy
Very noisy
Extremely noisy
Percentage (%)
Surgical (n=42)
Medical (n=40)
Figure 7.41 Patient perception of the day time ward noise environment
The patients who had indicated that they were annoyed by noise during the day, were then asked to
rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’
and 4 indicating ‘a great deal’. With a relatively small number of people annoyed by day time noise
the sample set was low (n=5 for the medical ward and n=11 for the surgical ward). Figure 7.42 shows
the percentage of patients within these samples who rated a noise event with a 2, 3 or 4, and as such
could be said to be more than a little annoyed by the event.
It can be seen that patients crying out, trolleys, internal telephones and rubbish bins (to a certain
degree) appear to be sources of annoyance in both wards. One particular difference is the doors
banging, rated by nearly 60% of patients on the surgical ward, but no one on the medical ward. As
discussed in the staff questionnaire section, there is one particularly heavy fire door at the end of the
ward corridor which was mentioned as a problem in initial discussions with staff.
Other noticeable differences are the annoyance caused by visiting time, footsteps, nurse call and
external noise. All these events are only cited by patients in the surgical ward. Due to the nature of
the surgical ward, with patients being taken up and down to X-ray and surgery, this may account in
part to the increased annoyance caused by footsteps. Occurrences of the nurse call were captured
more often and continuing for longer periods at the nurse station in the surgical ward (see Section
7.8.1), which explains the patient responses in this case. As discussed previously, external noise may
be more of a problem during the study period in the surgical ward as the weather was warmer and
more windows would have been open.
Talking on mobile phones and TV / radio are the only events that are cited by medical patients only.
This could be due to a lack of enforcement of mobile phone policy, and the non-compulsory use of
headphones.
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0 20 40 60 80 100
External noise
Doors banging
Nurse call
Footsteps
Visiting time
Staff talking on the telephone
Medical Equipment
People talking
Cleaning
Rubbish bins
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Internal telephone
Trolleys
Patients crying out
% of patients who rated each event 2 or above in terms of noise annoyance
Surgical (n=11)
Medical (n=5)
Figure 7.42 The percentage of patients rating an annoyance noise event with a 2, 3 or 4
Two patients in the medical ward added an additional noise event that they themselves found to be
annoying. The events were ‘a patient attention seeking’ and ‘the fan in the shower room’ (this was an
ensuite shower room in a single room). ‘Sirens’ and ‘the photocopier in corridor being used in the
evening’ were cited in addition by patients in the surgical ward.
Patients were asked how they perceived the night time noise environment on the ward. Figure 7.43
details the responses, where again the majority of the responses were split between ‘quiet’ and ‘a little
noisy’, but with a noticeably higher percentage (18%) in the medical ward choosing the ‘very noisy’
category than during the day.
When asked whether they were actually disturbed by noise at night, 58% of patients in the medical
ward felt they were, compared with 51% of patients on the surgical ward. This suggests that, in this
hospital, over 50% of patients are disturbed by noise at night.
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0 10 20 30 40 50
Very quiet
Quiet
A little noisy
Very noisy
Extremely noisy
Percentage (%)
Surgical (n=42)
Medical (n=40)
Figure 7.43 Patient perception of the night time ward noise environment
Patients who had indicated that they were disturbed by noise during the night were asked to rate the
annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’ and 4
indicating ‘a great deal’. Sample sets were higher than for the day time annoyance (n=23 for the
medical ward and n=19 for the surgical ward), indicating a much higher level of night time
disturbance. Figure 7.44 shows the percentages of patients within this sample who rated a noise
event with a 2, 3 or 4, and as such could be said to be more than a little disturbed by the event.
One noticeable difference that can clearly be seen is that ‘patients crying out’ seems to be much more
of a problem on the medical ward during the night. This is possibly related to the number of elderly
patients suffering from confusion and dementia on this ward, who tend to cry out more often.
It can be seen that certain events which were rated as annoying by only patients in the surgical ward
during the day, cause a level of night time disturbance in both wards. Doors banging, medical
equipment, trolleys and people talking are rated by similar percentages of patients on both wards.
However, the nurse call, the internal telephone and external noise are all rated as more disturbing on
the surgical ward. Occurrences of the nurse call were captured more often and continuing for longer
periods at the nurse station in the surgical ward, which explains the patient responses in this case.
As discussed previously, external noise may have been more of a problem during the study period in
the surgical ward as the weather was warmer and more windows would have been open.
As with daytime annoyance, ‘Talking on mobile phones’ is cited as a disturbance only on the medical
ward. The hospital policy specifies that mobile phones should only be used in the lobby areas and not
on the wards. This suggests a lack of policy enforcement by the staff on the medical ward.
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0 10 20 30 40 50 60 70 80 90 100
External noise
Footsteps
Rubbish bins
TV / radio
Mobile phones ringing
Internal telephone
Staff talking on the telephone
Nurse call
Trolleys
Talking on mobile phones
People talking
Medical Equipment
Doors banging
Patients crying out
% of patients rating night disturbance event of 2 or above
Surgical (n=19)
Medical (n=23)
Figure 7.44 The percentage of patients rating a disturbance noise event with a 2, 3 or 4
Six patients in the medical ward added an additional noise event that they themselves found to be
disturbing at night. The events were:
� Moaning, groaning and talking in sleep
� Dripping taps
� Noisy bed neighbours
� A patient admitted at night
� Private conversations between night staff, especially in native language
� Night staff having private conversations on mobile phones
One patient in the surgical ward also added ‘the supply cupboard door’ as an additional noise event.
This door had been mentioned by staff as a source of noise as it was a heavy metal roller shutter.
7.10.3. Positive sounds
Looking at sound in a positive rather than in a negative light, patients were asked if there were any
sounds that they actually found comforting. 70% of patients in the medical ward and 76% on the
surgical ward left the answer blank; however, there were twelve completed responses, which included
listening to music on the radio, knowing that the nursing staff were nearby to provide care, the tea
trolley, and maintaining some connection with the outside world. The full responses can be seen in
Appendix B.
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Respondents were also asked if they felt that there was ever too little sound in a room. Only 8% of
patients in the medical ward and 8% in the surgical ward said that they did. Surprisingly only one of
these respondents was in a single room.
7.10.4. Ease of hearing and privacy
Patients were asked whether high levels of background noise may at times make it difficult to hear
doctors and nurses who talk to them. 27% of respondents on the medical ward and 36% on the
surgical answered that this was the case.
Conversational privacy was investigated by asking whether the patients felt that they could have a
private conversation at their bedside. 100% of patients in single rooms said that they felt they could
speak privately, with lower percentages in the multi bed bays of 67% and 64% in the medical and
surgical wards respectively. Out of those who felt they could speak privately, around 40% said they
felt they could talk in their normal voice, with 60% needing to lower their voice or taking some other
precautionary measure – similar percentages were found in both wards.
7.11. Questionnaire comments
Staff and patients were invited to make additional comments at the end of the questionnaire if they
wished. Very few staff made comments, but many patients did leave some feedback which was very
varied. Several patients cited the kitchen and ward entrance as a source of noise, and one patient
suggested that the ward clerk’s desk, which acts as a ward reception, should be moved outside the
ward entrance. Mobile phones ringing in the night, large groups of visitors around a bed and loud and
aggressive patients were also mentioned. A detailed list of these comments is shown in the Appendix
B.
7.12. Summary
This section summarises the main findings from the study of the medical and surgical ward at Bedford
Hospital:
� Average noise levels measured at the nurse stations on both wards were similar both in level and
fluctuation patterns, with day time levels of around 55 dB LAeq. However, sources of high level
noise were found to differ, with the nurse call and high levels of conversation more prevalent at
the nurse station in the surgical ward, and furniture scraping and doors banging found more
frequently at the nurse station in the medical ward.
� Noise level measurements made in the multi-bed bays were very consistent in both level and
fluctuation patterns in both wards, except for 6-bed bay 3 in the medical ward where the levels
were higher. Patients crying out and increased clinical activity were found to account for these
increased levels.
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� Levels did not appear to be affected by increased bed numbers, that is, from four beds to six
beds.
� Single rooms were found to have less consistent patterns of noise levels and often had higher
levels than those measured in multi-bed bays. Behaviour of patients, visitors and clinicians was
shown to be the main cause.
� All measured levels were above those suggested by the WHO guidelines and the day / night
division specified by the WHO did not appear to be realistic.
� Although average noise levels were similar, subsequent investigation of the numbers of high
level noise events recorded in each bay indicated differences in the noise climate. For example,
in both wards, bay 1 is shown to be affected by noise from the ward kitchen, staff room and
particularly the ward clerk’s desk area. Questionnaire responses were found to reinforce this.
� Staff in both wards rated visiting time, medical equipment alarms and the internal telephone as
the most annoying noise events. Cleaning, people talking and staff talking were found to be more
annoying by staff on the medical ward, whereas the use of the nurse call, banging doors, trolleys
and external noise were found to be more annoying by staff on the surgical ward.
� Only 13% of patients on the medical ward, and 29% of patients on the surgical ward were
annoyed by noise during the day. Patients crying out, trolleys and internal telephones were the
main sources of day time annoyance on both wards, with doors banging, visiting time, footsteps,
the nurse call and external noise only cited by patients on the surgical ward.
� Higher percentages of patients were disturbed by noise at night, with 58% in the medical ward
and 51% in the surgical ward. The main differences found between the night time ward
environments were patients crying out and mobile phone use in the medical ward, and the use of
the nurse call, internal telephone and external noise in the surgical ward.
7.13. Conclusions
Noise level measurements and questionnaire surveys have confirmed that noise is a problem in both
medical and surgical wards. Staff responses indicate that they are annoyed by noise, and over half
the patients questioned felt that they were disturbed by noise during the night, a time when they
should be able to rest and recuperate.
The identification of high level noise sources has shown that in this hospital building the ward design
does appear to have a negative effect on patients located in some of the bays and rooms, specifically
bay 1 and the single rooms behind the main nurse station. By re-siting the ward clerk’s desk and
ensuring doors to the kitchen and staff room are kept closed, much of this unwanted sound could be
prevented. However, the two single rooms located directly behind the main nurse station is a more
difficult problem to address, with doors to the rooms left open to allow for patient observation.
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Noise levels did not appear to be related to occupancy levels, with similar levels measured in four and
six bed bays, and higher levels measured in single patient rooms than in multi-bed bays on
occasions.
Much of the high level noise identified could be reduced with changes to behaviour, correct
enforcement of hospital policies, simple improvements to design and maintenance of equipment. This
is discussed further in Chapter 12.
The following chapter investigates the effects of a refurbishment carried out in the medical ward at
Bedford Hospital. Reflective ceiling tiles in one four bed bay were changed for tiles with good acoustic
properties. Subsequent changes to noise levels and reverberation times are investigated and
reported.
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8. Ceiling intervention study, Bedford Hospital
8.1. Introduction
The medical ward in Bedford Hospital was due for refurbishment soon after the objective
measurements and subjective surveys (discussed in Chapter 7) were completed. This was to include
the replacement of the suspended ceiling tiles; a full repaint of all rooms; replacement of protective
wall panelling; and some general tidying and maintenance work.
Much of the existing suspended ceiling in the ward was known to have good acoustic properties, but
the large perforations in the tiles were felt to be unsuitable in light of the current control of infection
policy. Tiles of similar acoustic properties are now available on the market designed specifically for
hospital use. These tiles have a smooth finish and can withstand the bleaches and detergents
commonly used in hospital cleaning regimes. The author, working in conjunction with the hospital
estates team, suggested that these replacement ceiling tiles should be considered throughout the
ward. Although the tiles were slightly more expensive than the standard plain plaster tiles, the
purchase was agreed.
One bay was of particular interest to both the Estates team and the author. This bay had been
refurbished more recently than the rest of the ward and had a suspended ceiling of plain plaster type
ceiling tiles with poor acoustic properties. It was considered by both parties to be an excellent
opportunity to study the effects of changing the ceiling tiles, on the acoustic environment. The results
could then be used by the estates team to inform their decision making for further ward
refurbishments. Figure 8.1 shows the bay during refurbishment.
Figure 8.1 Photographs of the bay during refurbishment
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The study of the effects of the ceiling change in this bay discussed in this chapter, consists of two
parts: firstly the investigation of the effects of the ceiling change on the noise levels; and secondly the
effects of the ceiling change on occupied and unoccupied reverberation times.
8.2. Bay information
Bay 1 is the first open four bed bay immediately after the main entrance to the medical ward, and is
opposite the ward clerk’s desk, the staff room and the kitchen, as shown in Figure 7.10 in Section 7.5.
This particular bay was refurbished several years ago with a change from the original acoustic ceiling
tile to ‘Armstrong Bioguard Plain’ tiles. Although suitable for hospital use, these tiles have poor
acoustic properties. Figure 8.2 shows the manufactuer’s data on absorption coefficients for octave
frequency bands from 125 Hz to 4 kHz.
Figure 8.2 Absorption coefficients of Armstrong Bioguard Plain ceiling tiles
Source : Manufacturer’s product specification sheet
During the ward refurbishment, these tiles were changed for ‘Armstrong Bioguard Acoustic’ tiles.
Figure 8.3 shows the manufactuer’s data on absorption coefficients in frequency bands from 125 Hz
to 4 kHz for this tile. It can be seen that these tiles provide much greater acoustic absorption than the
previous ones, with particular improvement in frequencies from 500 Hz to 4000 Hz.
Figure 8.3 Absorption coefficients of Armstrong Bioguard Acoustic ceiling tiles
Source : Manufacturer’s product specification sheet
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8.3. Effect of ceiling tile change on noise levels
As part of the main study, occupied noise levels were measured in bay 1 over two separate weeks
prior to the ceiling change, as discussed in Section 7.6.2. For comparison purposes, the microphone
was suspended in the same position following the ceiling change and a further two weeks of data
were collected and compiled.
The first set of noise level data was collected with the bay occupied by female patients in April and
June 2010. The post ceiling change data were collected during December 2010 with male patients in
the bay. Apart from the time of year and the patient gender, there were no other known changes on
the ward, apart from the ceiling tiles. All ward routines remained the same.
Before any meaningful comparisons could be made between the pre and post ceiling change
measurements, the data were analysed in detail to see if any anomalies were present. Each trigger
file (created when LAmax exceeded 70 dB) was reviewed and all files were grouped by event type. The
average number of triggers over a 24 hour period was calculated for each event type both pre and
post the installation of the new ceiling tiles. Two anomalies caused by untypical patient behaviour
were identified and were considered to be worth further investigation: unusually high numbers of
triggers caused by patient cries during the pre ceiling change period; and the amount of coughing
after the ceiling change.
Further analysis of the trigger files showed that during the pre ceiling change measurement period
there was a very confused elderly lady in the bay who screamed whenever staff tried to sit her up or
get her out of bed. This caused a total of 278 individual triggers files (201 during the day and 77 at
night) over the period of one week which caused a increase in overall noise levels. It was felt that this
was an untypical event as there were no other episodes of this type during the subsequent weeks of
data collection. Therefore, to ensure that the data was comparable, this particular event was removed
for the analysis of noise levels.
The noise level measurements made after the ceiling change were carried out in December. This was
a particularly cold month and patients coughing caused a large number of trigger files during the
measurement period (on average more than 120 triggers were caused by coughing over 24 hours
compared with an average of 20 over 24 hours during the pre ceiling change period). As the ward was
not one that dealt with chest infections this was felt to be untypical of the noise climate on this ward. It
was decided that to provide a more realistic data comparison, the high numbers of coughs in the data
should be reduced to the average number found during the pre ceiling change period.
With the anomalies in the data removed, overall noise levels were calculated. Table 8.1 shows the
average LAeq measured during the day and night time pre and post the ceiling change. It can be seen
that day time and night time levels after the ceiling change are on average 2.4 dB and 3.4 dB LAeq
respectively lower than levels before the change.
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Table 8.1 Average LAeq measured during the day and night time pre and post the ceiling change
Position in ward A-weighted equivalent sound pressure levels
Day time Night time
LAeq, 16hr LAeq, 8hr
Pre ceiling change (2 weeks) 53.7 45.2
Post ceiling change (2 weeks) 51.3 41.8
20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Pre ceiling change Post ceiling change
Night time
Day time
Figure 8.4 Average LAeq,1hr levels over 24 hours pre and post ceiling change
Figure 8.4 shows the average LAeq,1hr levels measured over 24 hours pre and post the ceiling change.
Fluctuations in level follow the same pattern, suggesting that ward routines are unchanged, but the
levels are consistently lower.
The decrease in the overall measured noise levels suggests that the acoustic ceiling tiles are having
some positive effect. This can be further substantiated by looking in more detail at the high level noise
sources before and after the ceiling change, with the anomalies removed. Figure 8.5 shows the
number of high level noise events captured; that is events where LAmax exceeds 70 dB. Any notable
differences are highlighted.
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0 10 20 30 40 50 60 70 80 90 100 110 120 130
Unidentifiable
Conversation between staff
Staff and patients talking
Patients talking
Patient talking on phone
Patient procedures
Cough / sneeze / gurgling / groaning / snoring
Rubbish bin
Laughter
Shoes squeaking on floor
Patient calling out
Furniture scraping
Ring binder / admin at nurses' desk
Cleaning
Cupboard door / drawers
Tea / drinks round
Meal time
Bathroom door
Trolley
Visiting time
Noise from corridor / kitchen
Mobile phone ringing
Average number of trigger files recorded in 24 hours
PRE ceiling change
POST ceiling change
Figure 8.5 Average number of trigger files recorded over 24 hours by event type
It can be seen in Figure 8.5 that there are notable reductions in the numbers of high level noise
events associated with visiting time, patient procedures and staff and patients talking. These events
include speech, a frequency range at which the new ceiling tiles are known to be particularly
acoustically absorbent which may explain these reductions. The numbers of high level noise events at
meal times and during cleaning are also reduced, as are the number of unidentifiable events.
Figure 8.6 shows the frequency content of a typical high level noise event associated with meal time,
that is, metal cutlery scraping on a china plate, which was recorded before the ceiling change. It can
be seen that the levels are higher at the low frequencies, decreasing steadily from around 150 Hz to
around 1 kHz, and then rising again in the frequency bands at which the ceiling tiles are most
effective. It is therefore unsurprising that the new ceiling tiles, which provide more absorption at high
frequencies, are having some positive effect on noise events of this type.
Figure 8.6 The frequency content of metal cutlery
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8.4. Effect of ceiling tile change on reverberation time
Reverberation time (RT) is generally used as an indicator of the acoustic comfort of a space and is an
important measurement in the field of room acoustics. As discussed in Section 5.3.8, any RT
measurements made in unoccupied wards were carried out using the Impulse Response Method with
balloon bursts as the source of noise. In occupied wards, where physical RT measurements are not
possible, an estimation method is used. As explained in Chapter 1, data collected in this study have
been used to validate an estimation method developed at the University of Salford (Kendrick, 2009).
The validation is discussed in more detail in Chapter 10. The reverberation times for occupied wards
presented in this Section 8.4.2, have been estimated using this method.
8.4.1. Unoccupied reverberation times
RT measurements were carried out in the unoccupied bay using the Impulse Response Method just
prior to, and just after the ceiling tile change. In total twelve RT measurements were made, six before
the ceiling change and six after. Figure 8.7 shows the layout of source and receiver positions, with the
following combinations of source and receiver positions used: S1-R1; S2-R1; S3-R1; S1-R2; S2- R2;
S4-R2.
Figure 8.7 Source (S) and receiver (R) positions used to measure reverberation time in the
unoccupied bay before and after the ceiling change
Although the bay was unoccupied during the RT measurements, there was some furniture piled in the
centre of the bay on both occasions, as shown in the photographs in Figure 8.1. This may have
S1
S3
S2 S4
R1
R2
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provided some small amount of acoustic absorbency, but was in place during both sets of
measurements and as such may affect the overall RT values, but should not affect the differences.
Figure 8.8 shows the spatially averaged RT20 values over third octave bands from 250 Hz to 4 kHz as
stipulated in BS EN ISO 3382-2 (2008). The error bars show the 95% confidence limits of the mean
values. It can be seen that at all frequencies the measured RT20 values have decreased after the
ceiling tile change, by between 0.1 s and 0.4 s, with the greatest changes above 500 Hz. Given that
these are the frequencies at which the tiles have the highest absorption coefficients, these results are
as expected. The 95% confidence limits are generally small, particularly at the higher frequencies,
suggesting little variation between the measured values at each frequency.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k
Me
an
RT
20
(s)
Frequency (Hz)
Pre ceiling change
Post ceiling change
Figure 8.8 Average unoccupied RT20 measurements with 95% confidence limits
(Impulse Response Method)
Bork (2000) shows that in a room with an RT value of 2 s or less, the subjective difference limens are
0.1 s, and hence any change in the RT that is less than 0.1 s would not be noticeable to the listener.
In this case however, the changes of between 0.1 s and 0.4 s exceed this difference limen, and as
such would be perceived by the occupants of the bay.
8.4.2. Occupied reverberation times
Using trigger files captured during the measurement period before and after the ceiling change,
reverberation times of the occupied bay were estimated using the Maximum Likelihood Estimation
Method (MLE-RT20) which is discussed fully in Chapter 10.
Over 5000 individual trigger files were processed to produce each octave band MLE-RT20 estimate
from 250 Hz to 4 kHz. As would be expected the estimated values for the occupied ward are lower
than the measured RTs in the unoccupied ward, by up to 0.3 s at 4 kHz both pre and post the ceiling
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change .This is due to the absorbency of the additional furniture, bedding, curtains and the occupants
themselves.
Figure 8.9 shows the estimated MLE-RT20 values before and after the ceiling replacement. As with
the values measured in the unoccupied bay, it can be seen that the addition of the acoustic ceiling
tiles has reduced the MLE-RT20 values by up to 0.1 s in each of the octave bands estimated. The
largest differences are in the 1 kHz to 4 kHz frequency bands, where the reduction in MLE-RT20 is
greater than 0.1 s. This is as would be expected as these are the frequencies where the new ceiling
tiles are particularly effective. The reduction in the MLE-RT20 estimate is much less at 500 Hz, and at
250 Hz the 95% confidence limits of the pre-replacement estimate are ±0.13 s and therefore the
results at this frequency should be ignored.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
250 500 1000 2000 4000
Est
ima
ted
MLE
-RT
20
(s)
Octave band (Hz)
Pre ceiling
replacement
Post ceiling
replacement
Figure 8.9 Occupied MLE-RT20 estimates pre and post the ceiling replacement,
8.5. Comparison of unoccupied and occupied RTs
The estimated MLE-RT20 values shown in the previous section not only reinforce the effect of the
ceiling tile change on the room acoustic, they also provide useful information regarding the amount of
acoustic absorption in an occupied four bed bay, and the effect that this extra absorption has on the
reverberation time. Tables 8.2 and 8.3 show the reverberation times measured in the unoccupied bay
alongside the estimated MLE-RT20 values when the bay is occupied, both before and after the ceiling
change.
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Table 8.2 Reverberation times for both the unoccupied and occupied bay pre ceiling change
Frequency (Hz)
Pre ceiling change - measured RT20 (s) in unoccupied bay
Pre ceiling change - estimated MLE-RT20 (s) in occupied bay
Decrease (s)
250 0.64 0.63 0.01
500 0.65 0.44 0.21
1 k 0.69 0.42 0.27
2 k 0.69 0.42 0.27
4 k 0.70 0.38 0.32
Table 8.3 Reverberation times estimates for both the unoccupied and occupied bay
post ceiling change
Frequency (Hz)
Post ceiling change - measured RT20 (s) in
unoccupied bay
Post ceiling change - estimated MLE-RT20 (s) in
occupied bay
Decrease (s)
250 0.51 0.39 0.12
500 0.42 0.33 0.09
1 k 0.29 0.27 0.02
2 k 0.36 0.29 0.07
4 k 0.38 0.27 0.11
It can be seen from Tables 8.2 and 8.3 that in the more reverberant room (pre ceiling change) the
difference in reverberation times at 1 kHz between the unoccupied and occupied space at 500 Hz and
above is greater than 0.2 s. However, with the ceiling changed, there is a negligible difference
between the unoccupied and occupied reverberation times at those frequencies. As discussed in
Section 8.4.2 the results at 250 Hz are unreliable and therefore this estimate should be ignored.
8.6. Conclusions
This chapter clearly illustrates the benefits of the installation of an acoustic ceiling, which results in
consistently lower measured average noise levels and a decrease in reverberation times (from 0.7 s
to 0.3 s at 1 kHz in the unoccupied room). Notable reductions in the numbers of high level noise
events associated with visiting time, patient procedures, conversation, meal times and cleaning were
also found after the ceiling change.
This intervention study has also provided interesting data regarding the level of acoustic absorption
provided by the occupants and soft furnishings in a 4-bed bay, with a reduction in the reverberation
time of over 0.2 s at most frequencies in the bay before installation of an acoustic ceiling. After the
addition of a large area of acoustic absorbency in the form of a ceiling, the effects on the room
acoustics of the occupants and soft furnishings becomes negligible.
The following chapter presents the results of the objective and subjective surveys at Addenbrooke’s
Hospital, Cambridge while Chapter 10 gives details of the method used to estimate the occupied RTs
and its validation using data collected from both Bedford and Addenbrooke’s Hospitals.
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9. Addenbrooke’s Hospital
9.1. Introduction
Three wards at Addenbrooke’s Hospital also formed part of the subject of the main study which took
place over an eight month period from April to November 2010. To provide comparisons between
buildings of different age, construction type and ward layout, three wards were identified for the study
following liaison with the Estates team: a 1970’s tower block of brick and concrete construction; a
recently opened modular block of timber construction; and a privately funded building completed in
2006 and built to adhere to the latest acoustic design standards
The study wards also provided useful comparisons in terms of the types of patient accommodation
and care offered. Ward D8, situated in the 1970’s tower block, is a trauma and orthopaedic ward. This
ward is large and has a mixture of accommodation ranging from 3-bed bays through to a 12-bed bay.
Care is offered to a diverse group of patients; some with severe injuries as a result of road accidents;
some with injuries resulting from elective surgery; others suffering from both physical trauma and a
level of dementia. Ward N3, situated in the modular block, is a respiratory ward for both acute and
chronically sick patients and contains a specialist respiratory unit to care for patients who require non-
invasive respiratory ventilation. Accommodation provided here is a mix of single rooms and 4-bed
bays. Ward M4, situated in the privately funded Addenbrooke’s Treatment Centre, is a surgical ward
specialising in urology. Accommodation provided here is again a mix of single rooms and 4-bed bays.
9.2. Background
Addenbrooke’s Hospital opened in 1766 and was one of the first provincial, voluntary hospitals in the
UK. By the 1950’s the hospital had started to outgrow its original site and in 1959 building began on a
new 66-acre site south of Cambridge, with the first phase of the new hospital opening in May 1962.
Figure 9.1 Original building, Addenbrooke’s Hospital
Now, nearly 250 years after its inception, the hospital provides emergency, surgical and medical
services for people living in the Cambridge area and offers regional specialist services for organ
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transplantation, cancer, neurosciences, paediatrics and genetics. Bed numbers currently stand at
1200, with 7000 staff employed and annual inpatient admissions at around 180,000. The site now
includes a dedicated maternity and women’s hospital, The Rosie, with deals with around 5800 births a
year.
9.3. Ward D8 (surgical)
Ward D8 is situated on the eighth floor of the 1970’s tower block, known as C & D block. This is a
trauma and orthopaedic ward dealing with trauma as a result of an accident and performing elective
therapeutic interventions, for example, for problems caused by wear and tear to the hips, joints and
shoulders. The ward has total of 35 beds and is the second largest in terms of bed numbers on the
Addenbrooke’s hospital site. This ward is divided between three single rooms, three 3-bed bays, a 4-
bed bay, a 7-bed bay and a 12-bed bay.
Thirteen out of 35 patient beds on this ward are dedicated to care of elderly female patients. These
beds, collectively known as the ‘elderly trauma unit’, consist of two 3-bed bays and a 7-bed bay and
have the highest intervention of nursing on the ward, with four nurses to 13 patients. The unit treats
those over 75 years of age who have been involved in an accident, or for example, have broken their
hip as a result of a fall. Often these patients are suffering from a number of other complaints such as
confusion, dementia or delirium, and consequently this section is considered to be noisy by the ward
manager, with patients calling out and banging objects. Elderly male patients admitted to the ward are
placed in the standard male accommodation.
9.3.1. Building design
C & D block is a 10 storey naturally ventilated tower block constructed in the early 1970’s. Brick built
with cavity walls and concrete floors, it is unknown whether it was built to comply with any particular
acoustic standard. The building is a mirror image designed around a central lift shaft and stairwell,
with C section on one side and D on the other.
Internally, apart from general maintenance, the replacement of single glazed windows with double
glazed units, and some redecoration, very little has changed since the building was completed.
However the wards, which were originally built to house a total of 24 beds, now contain up to 35 beds.
Bed spacing is considered to be very poor, leading to a compromise in privacy and dignity. To
illustrate this lack of space further, the ward area of D8 is 850 m2 compared to 1250 m
2 in ward M4
which is situated in the recently opened, privately funded treatment centre, and provides only 28
patient beds.
The study ward, ward D8, has little in the way of acoustic absorbency at ceiling level. Most ceilings
consist of metal pan tiles which work in conjunction with the heating system, by radiating heat from
the hot water pipes running above them. These tiles are perforated, with a layer of insulation covering
the water pipes. This may provide some level of acoustic absorbency at certain frequencies, but this
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is unknown. An exception to this is the 4-bed female bay situated behind the nurse station, which has
a suspended ceiling grid with solid plaster tiles. Other acoustic absorbency on the ward is provided by
privacy curtaining which can be pulled fully around each bed; window curtaining; mattresses and
bedding. All patient accommodation has heavy duty vinyl flooring and solid plaster walls.
9.3.2. Ward layout
Senior staff offices and the main ward reception area are positioned in the central lobby area which
separates C and D wards. A card swipe system is in operation to allow access to ward D8, which is
designed around a long interior corridor, with the majority of patient accommodation on one side, and
a male 12-bed bay situated centrally at the end of the corridor. Healthcare utilities, a staff room, ward
kitchen, day room and three single rooms are situated on the opposite side. There is also a service lift
for patient transportation and ward deliveries. Ensuite toilets are provided in each bay, but single sex
bathrooms are situated at each end of the corridor. A ward plan is shown in Figure 9.2 on page 150.
The 12-bed and 3-bed bays at the end of the ward are male only. The male patients use the toilet and
bathroom facilities at this end of the ward corridor to ensure same sex segregation. There is a small
nurse station in the centre of this 12-bed bay, with a PC and telephone, which may be a source of
some noise, especially at night.
The main nurse station is situated directly outside the 4-bed female bay and opposite the three single
rooms. Again, a potential source of noise, this area is often bustling with staff and is where the ward
clerk is based during office hours.
The remaining bays house the ‘elderly trauma unit’, which are opposite the healthcare utilities, staff
room, and assisted bathroom and ward kitchen.
Compared to wards in newer buildings, such as M4 and N3 (the other study wards on this site), this
ward feels rather cluttered, with a general lack of storage space, and a narrow dark central corridor.
9.3.3. Ward specific information
The doors to all bays are always left open for observation purposes, with single rooms generally used
for infectious patients. If barrier nursing is required, the doors to the single rooms are closed. The
ward runs at a very high occupancy level, of around 99%.
Staffing levels and shift patterns
Staffing levels are highest from 07.15 until 15.15, with ten nursing staff present, seven days a week.
This reduces to seven nursing staff for the afternoon shift and to six for the night shift, which lasts
from 19.15 to 07.15. Other staff members include a ward clerk who works during office hours from
Monday to Friday, and six therapists who work with the patients on weekdays and weekend mornings.
There are 13 consultants and seven registrars serving this ward. The doctors’ rounds generally take
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place in the morning and during this time there could be between eight and ten doctors on the ward.
At weekends the number of doctors drops to three.
Three domestic staff also work from 08.00 to 16.00, with an additional staff member working from
16.00 until 20.00. One of these staff members is dedicated to cleaning (moping, damp dusting,
changing beds and picking up litter); the other two are housekeepers and are more involved in serving
food, beverages and replenishing water jugs. The member of staff working the later shift plays a dual
role.
Ward routines
The first patient visits by clinicians are around 06.00 for general observation, dispensing of drugs and
theatre preparation. However, general activity on the ward does not begin until 06.50 when the main
lights are switched on.
Morning shift handover takes place between 07.15 and 07.45 in the day room, staff room and at the
main nurse station in the corridor. After the handover the night staff accompany the day staff to their
charges to discuss the patient’s progress and examine their notes. There can be as many as six
people at the end of the patient’s bed at this time.
From 08.00 onwards the ward is very busy with nurses attending to their patients and the arrival of
surgeons, therapists, domestic staff and the ward clerk. The ward does not begin to calm down again
until late morning when the nursing staff have a break from the patients and have a chance to catch
up on phone calls and other administrative aspects of their jobs.
From 14.00 until 15.00 there is a designated rest period on the ward which is primarily to help patients
get some rest before visiting time begins.
Drug rounds and patient observations continue throughout the day at noon, 17.00, and 21.00.
A second shift handover takes place when the night staff arrive, between 19.15 and 19.45. As with the
morning handover, the day and night staff visit their patients, check notes and discuss patient
progress.
The ward lights are finally dimmed around 23.00. During the night patients who are particularly unwell
have further observations taken at 02.00.
Meal times
A cold breakfast of cereal and toast is prepared in the ward kitchen and served from a trolley from
08.15 to 09.30. This is followed by a hot drinks trolley at 10.00. A hot lunch arrives on the ward at
midday and is plated up in the corridor. A selection of cold supper options is served at 17.00.
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Visiting times
The official hours for visiting time are 15.00 until 20.00.
Sources of noise on the ward
The following are thought to be the main sources of noise by the ward manager:
Doorbell
There is a buzzer but it is not felt that this is particularly loud
Nurse Call
This system has a changeable volume, but is never turned up very loud, even during the day.
Telephones / PCs / fax / printers
There are four telephones, three PCs, a fax and printer at the main nurse station, and other
telephones and PCs on staff desks in the larger multi-bed bays.
Patientline
This TV, radio and telephone system is available here at a cost. Headphones are provided and any
patient not using them would be asked to make use of them for watching TV or listening to the radio.
Medical Equipment Alarms
Plaster removal
No treatment room is available on this ward and plaster casts are removed at the bedside.
Deliveries
Ward deliveries come up to the ward via the service lift. Large deliveries, such as linen, are delivered
in wheeled cages and are generally left in the corridor. Smaller deliveries include pharmacy items.
9.3.4. Managing the study
The ward manager was very supportive of the study and made every effort to ensure that full
cooperation was provided by the ward staff. There were no undue concerns regarding the cleaning of
the noise measurement equipment and the ward manager spent several hours of his time identifying
possible microphone positions that would be acceptable to staff and patients. For comparison
purposes it was important that the microphone was placed in similar locations in each accommodation
type. A ward plan showing the microphone positions can be seen in Figure 9.2.
To avoid the microphone being knocked or contaminated, and in order for it to be as unobtrusive as
possible, it was felt that suspending the microphone from the ceiling would be ideal. An identical 300
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mm bracket to that used successfully at Bedford Hospital was used to suspend the microphone from
the ceiling at each measurement position.
Questionnaires were reviewed by the ward manager and it was decided that they would be distributed
by the ward clerk to those patients who had been on the ward for over 24 hours and were felt to be fit
enough to complete the survey. Staff questionnaires were to be left for staff to complete in the staff
room.
As with the pilot study, a number of laminated posters were displayed throughout the ward common
areas. These posters were aimed at both staff and patients and explained in simple terms why and
how the study was being undertaken. In addition to these posters the ward manager personally
discussed the study with all his staff during staff meetings.
Figure 9.2 Detailed plan of ward D8 showing microphone positions
Microphone position
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9.4. Overall acoustic survey results Ward D8
Noise level measurements were made at six different locations on the ward. Table 9.1 shows the
locations and the time periods of all measurements made, and the patient genders where applicable.
Unfortunately it was not possible to make measurements in the single rooms on this ward due to the
infectious conditions of the patients.
Table 9.1 Ward D8 - measurement locations, time periods and patient gender / types
Position Length of measurement period Patient gender / type
Nurse station 6 days N/A
12-bed bay 2 non-consecutive weeks (14 days) Male
7-bed bay 6 days Elderly
4-bed bay 8 days Female
3-bed bay A 7 days Male
3-bed bay B 7 days Elderly
Overall measurements of A-weighted equivalent sound pressure levels (LAeq) were averaged and are
shown for 24 hours, day time and night time in Table 9.2.
Table 9.2 Average LAeq measured for 24 hour, day and night time periods at each location.
Position in ward Week average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Nurses Station 57.0 58.1 52.9
12-Bed Bay Week 1 55.4 56.9 47.1
12-Bed Bay Week 2 56.4 57.9 48.2
7-Bed Bay 56.4 57.8 49.4
4-Bed Bay 54.3 55.6 48.5
3-Bed Bay A 55.0 56.5 47.1
3-Bed Bay B 56.5 57.8 50.7
A summary of the day and night time average levels presented in Table 9.2 are presented graphically
in Figure 9.3 for clarity. As with the wards at Bedford Hospital, levels in all patient accommodation
exceed those suggested in the WHO guidelines without exception. Little variation can be seen within
the day and night time average noise levels for the patient accommodation, despite the wide range of
patient numbers (3 to 12), with day time levels ranging from 55.6 to 57.9 dB LAeq, 16hr and night time
levels ranging from 47.1 to 50.7 dB LAeq, 8hr. Day and night levels at the nurse station are, as expected,
higher than those measured in the patient accommodation.
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In terms of the drop in level between day and night, only a relatively small drop of 5 dB was observed
at the nurse station, which is comparable with nurse stations on the study wards at Bedford Hospital.
This is unsurprising as the nurse station is staffed at all times. The male bays showed the greatest
drop in level between day and night of around 10 dB, which is unexpected as one of the male bays
measured was the largest bay in the study, containing 12 beds. The elderly patient bays and female
bays showed a slightly lower day to night drop of around 7.7 dB, which could possibly be related to
patients crying out.
0
5
10
15
20
25
30
35
40
45
50
55
60
65
Nurses Station 12-Bed Bay 3-Bed Bay A 3-Bed Bay B 7-Bed Bay 4-Bed Bay
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Day
Night
Figure 9.3 Average day and night LAeq levels measured at each location
Detailed results of levels measured at the nurse station are discussed in the next section, with further
results from the multi-bed bays shown in Section 9.4.2.
9.4.1. Nurse station
Figure 9.4 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station. It can be
seen that the lowest average ambient noise levels are recorded during the later part of the night,
where they are around 50 dB LAeq. From 05.30, levels increase steadily and peak at 11.30 when the
staff are free to catch up with administrative tasks and telephone calls and are therefore working at
the nurse station. Levels remain fairly constant at around 59 dB LAeq during the middle part of the day,
with a slight dip following lunch and during the patient rest period. Levels then begin to decrease
around 16.00, peaking briefly again during the evening shift handover and then do not decrease
substantially until 23.30. This pattern follows the ward routines described in Section 9.3.3. The night
time background levels remain very constant at around 42 dB LA90, while day time background levels
peak in the middle of the day at around 48 dB LA90.
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20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Nurse station LAeq Nurse station LA90
Night time Day time
Figure 9.4 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station
Viewing averaged noise levels over time, as in Figure 9.4 above, provides valuable information with
regards to level consistency and overall day and night time variation patterns, but does not illustrate
the fluctuating nature of noise in the short term. Figure 9.5 shows noise levels captured at the nurse
station over a ten minute time interval at 04.30 with the microphone approximately 1.5 m away from
the main desk area. Using the trigger files captured when LAmax exceeds 70 dB, certain high level
noise events have been identified.
Figure 9.5 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a ten minute interval at the
nurse station during the night
The sources of high level noise shown in Figure 9.5 are a good representation of types of high level
noise captured at this nurse station during the night and are predominantly related to the
RINGER
BINDERS DESK DRAWERS
SHUTTING
FURNITURE
SRAPING
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administrative tasks undertaken by the staff. Identified events consist mainly of the closing of ring
binders, furniture scraping on the floor and desk drawers shutting.
Day time high level noise at the nurse station was found to be mostly due to conversation, with some
noise again associated with administrative tasks and some occurrences of the internal phone.
Although in use on the ward, the nurse call system and doorbell were not captured as sources of high
level noise. As discussed in Section 9.3.3, the ward manager confirmed that the volume of both these
systems is deliberately turned down.
To further illustrate the types and noise levels of typical high level events at the nurse station,
examples are presented in Table 9.3. It should be noted that the levels shown are for individual
events and may not be representative of every noise event of that type.
Table 9.3 Examples of noise events at the nurse station
Noise event LAmax (dB)
Furniture scraping 78
Ring binder 85; 90
Desk draw shutting 81
Internal telephone 68
9.4.2. Multi-bed bays
Figure 9.6 shows the averaged LAeq,1hr levels measured over 24 hours for two 3-bed, a 4-bed, a 7-bed
and 12-bed bay. It is clear from the figure that although the numbers of beds in the bays vary
considerably, there does not to appear to be a relationship between bed numbers and noise levels,
with some of the highest levels measured in the elderly 3-bed bay. Interestingly, the largest bay (12
beds) actually shows one of the lowest averaged LAeq,1hr levels during the night.
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20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
, 1
hr)
Time (24h:00)
12-Bed Bay (Male) 7-Bed Bay (Elderly) 4-Bed Bay (Female) 3-Bed Bay (Male) 3-Bed Bay (Elderly)
Night time Day time
WHO GUIDELINES
Figure 9.6 Average LAeq,1hr levels over 24 hours for the multi-bed bays
The figure also shows that the WHO day / night division is not a particularly good fit. Noise levels
increase steadily from around 05.30 rather than 07.00, and begin to decrease after the evening meal
is served and then further decrease at 23.00. This suggests it might be appropriate to redefine the
‘day’ and ‘night’ time periods for hospital noise assessment and perhaps consider the addition of an
‘evening’ period.
The measured levels essentially follow some very general patterns, climbing steadily as morning
activity increases on the ward; peaking as lunch is served and then decreasing slightly during the
patient rest period. Levels increase again during the afternoon reflecting additional noise generated
during visiting times, and then begin to decrease after the early evening meal. This ward is large, with
a diverse group of patients; some with severe injuries as a result of road accidents; some with injuries
resulting from elective surgery; others suffering from both physical trauma and a level of dementia.
Due to this diversity very different levels and types of care are required on this ward. This in itself
leads to less well defined routines of patient care and hence more variation in measured noise levels.
This is not necessarily the case in other study wards which deal with more specific types of medical
problems or surgical procedures.
Further analysis of high level noise sources is carried out in the next section.
9.4.3. Further analysis of high level noise sources
Average LAeq,1hr levels over 24 hours, as presented in the previous section, provide some general
comparisons and show fluctuations related to ward routines. However, to build up a more detailed
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picture of the sources of high level noise at each location, the numbers of occurrences of LAmax in 5 dB
bands from 70 to 95 dB have been examined. Figures 9.7 and 9.8 show the average number of high
level noise events captured during the day and night in different measurement locations.
It can be seen in Figure 9.7 that apart from the nurse station, which has already been discussed in
some detail in Section 9.4.1, the largest numbers of day time high level noise events are recorded in
the 12-bed bay, closely followed by two bays in the elderly trauma unit. This is interesting as the
average noise level in the 12-bed bay is very similar to that in the other bays, see Table 9.2 and
Figure 9.6. This is a good illustration of why it is necessary to break the data down and fully
understand the content of the noise, rather than relying on overall noise levels.
0
100
200
300
400
500
600
700
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
90 ≤ LAmax < 95 dB
Figure 9.7 Average number of high level noise events recorded at each location per day
The 12-bed bay has a small desk situated in the centre of the ward with several PCs and a telephone.
For logistical purposes the microphone was suspended above this area and thus many of the high
level noise sources captured were related to nurse activity at or around this desk, including
conversation; talking on the telephone; and the use of ring binders. This desk area was open to the
ward and thus any high level sounds captured here would be heard by the patients on the bay. This
area was busiest during the day, however high level noise attributable to administrative tasks was
also captured during the night – a potential disturbance to patients on the bay. Other high noise levels
captured can be attributed to the furniture scraping on the floor; the drinks cup dispenser; the jangling
of crockery and cutlery at meal times; general movement around the ward and conversation at visiting
times. The corridor to the bathroom was situated behind the microphone, and doors banging were
often captured at high levels.
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The 7-bed and 3-bed bays in the elderly trauma unit had many more high level noise events
associated with patients calling out and clinicians talking to patients loudly. This had been expected
by the ward manager. Patients here are often very confused or distressed, and so to try and engage
with, and subsequently comfort the patients, clinicians need to raise their voices.
It can be seen in Figure 9.8 that apart from the nurse station, the largest numbers of night time high
level noise events are recorded in the elderly trauma unit. As many of the patients are woken up
before the designated start of day (07.00), many of the high level sources of noises are related to
distress and confusion during this process, which occurs between 06.30 and 07.00. Although listed as
night time noise, this gives a misleading indication that these bays are noisy throughout the night,
which is not generally the case. The high noise levels during this time are further illustrated by the
noise level trace shown in Figure 9.9, which clearly demonstrates high levels of noise from 06.41 to
07.00, much of which can be attributed to a confused patient crying out and the staff trying to calm
them. The blue line represents the average LAeq,8hr measured in the bay during the night, further
highlighting the high levels of noise shown here.
0
20
40
60
80
100
120
Nu
mb
er
of
reco
rde
d n
ois
e e
ve
nts
by
cate
go
ry
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 9.8 Average number of high level noise events recorded at each location per night
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Figure 9.9 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 19 minute interval
in the elderly trauma unit
To illustrate the types and noise levels of typical high level events found in the multi-bed bays,
examples are presented in Table 9.4. It should be noted that the levels shown are for individual
events and may not be representative of every noise event of that type.
Table 9.4 Examples of noise events in the multi-bed bays
Noise event LAmax (dB)
Bed rails 84
Patients crying out 85 - 91
Drinks cup dispenser 78
Shoes squeaking on floor 74
Trolley 73
Medical equipment alarm 71
It can be seen in Table 9.4 that patients crying out are measured at levels from 85 to 91 dB LAmax.
Such high noise levels would undoubtedly cause disturbance to other patients on the bay.
9.4.4. Representative measurement interval
In Chapter 6 it was established that a representative measurement interval was one week in duration
(5 days when the ward occupancy decreased at weekends). It was felt important that this
measurement interval was validated during the main study when it was possible to measure two non-
consecutive weeks’ worth of noise level data in the same bay. Noise level measurements in the 12-
bed male bay were captured for two seven day periods, several weeks apart. Figure 9.10 shows the
averaged LAeq,1hr levels measured during the two measurement periods. It can clearly be seen that the
averaged levels are similar in both level and fluctuation. A χ2 goodness of fit test found no statistically
significant difference between the two datasets at the 1% level.
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20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
Week 1 Week 2
Night time
Day time
Figure 9.10 Average LAeq,1hr levels over 24 hours for two non-consecutive weeks in the 12-bed bay
It can therefore be said that a seven day measurement interval is representative interval for the 12-
bed bay, and reinforces the findings of the pilot study, that one week’s worth of data (5 days when the
ward occupancy decreased at weekends) is a representative measurement interval for the study.
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9.5. Ward N3 (medical)
Ward N3 is situated on the third floor of a new modular wing. It is a respiratory ward for both acute
and chronically sick patients and contains a specialist respiratory unit to care for patients who require
non-invasive respiratory ventilation. The ward has a total of 25 beds divided between nine single
rooms; two 4-bed bays (one male and one female); and a respiratory care unit which contains two
adjoining 4-bed bays (one male and one female).
The ward generally runs at 100% occupancy. Weekends may be slightly quieter as there are no
routine tests carried out, but occupancy levels remain the same.
9.5.1. Building design
Completed in 2009, this modular block is of mainly timber construction, double glazed with both
mechanical and natural ventilation. Built to comply with acoustic standard HTM 2045, the suspended
ceiling grid is fitted with Ecophon acoustic tiles with good absorption properties; the plasterboard stud
walls are sound insulated with 50 mm of mineral wool in the cavity; and the floor is heavy duty vinyl on
flooring grade ply, again well insulated in the void.
Interestingly, staff working on this ward have found that the floor (which is timber and a little springy)
has had a detrimental effect on their feet. The design of the ward, which is ‘L’ shaped, also makes the
staff cover quite large distances each day, potentially adding to this detrimental effect. Complaints
regarding the floor were so widespread that remedial work has been carried out to stiffen the floor
slightly since it was first constructed. Feedback from staff suggests that this is generally felt to be an
improvement.
The Estates team were particularly interested to see whether this particular building, which is of
untypical construction, suffered from any unusual noise problems. It was not envisaged that these
would be related to sound attenuation, but it was considered that the floor construction could
potentially magnify certain sounds.
9.5.2. Ward Layout
As can be seen in Figure 9.11 on page , the ward is ‘L’ shaped with patient accommodation, staff
offices and healthcare utilities on both sides of a long central corridor. The entrance to the ward is at
the top of the ‘L’, with the patient multi-bed bays situated on the longer section of corridor and the
single rooms on the shorter section. The siting of the single rooms in this way potentially means less
traffic flow in the corridor, as apart from a store at the very end of the ward, there is no reason to walk
past the single rooms unless going to see a patient. All patient accommodation has full ensuite
bathroom facilities.
The nurse station is centrally located at the corridor intersection. It is opposite the 4-bed female bay,
the clean and dirty utility rooms and storeroom, with a drug preparation room behind. It may be a
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source of noise to the female patients in the opposite bay, as not only is the nurse station itself busy,
but staff are constantly opening and closing the doors to the utility rooms and store. The other staff
administrative areas are situated close to the ward entrance, with the ward clerk’s desk area, seminar
room and general offices based here. The respiratory care unit which contains two adjoining single
sex 4-bed bays has its own nurse station.
9.5.3. Ward specific information
Doors
Doors to the 4-bed bays and single rooms are kept open at all times, except if a patient is infectious
and requires barrier nursing (this applies to single rooms only).
The doors to the respiratory care unit are shut at night as this ward is perceived as quite noisy due to
the amount of equipment in use. This unit has its own dedicated nurse station, which enables the
doors to be closed.
Staffing levels and shift patterns
Staffing levels are highest on the day shift, from 07.15 to 19.15, with eight nursing staff present. This
reduces to five nursing staff for the night shift which lasts from 19.15 to 07.15. Other staff members
start work at 08.30, and include a ward clerk; four physiotherapists; two occupational therapists; and
four other assistants who are either pharmacists or are involved in collecting bloods. There are eight
doctors serving this ward, with the doctors’ rounds generally beginning around 10.00 and continuing
into mid- afternoon. Four domestic staff also work on the ward, cleaning and serving meals and drinks
During weekends there are slightly fewer staff with six staff nurses and one healthcare assistant.
Ward routines
The first patient visits by clinicians occur at around 06.00 for general observation; however, general
activity on the ward does not begin until 07.15 when the main lights are switched on. The morning
shift handover also takes place at this time and is carried out at the bedside, where there are
generally three members of staff present.
At 08.00 the first drug round begins and staff begin to get patients up ready for breakfast. The majority
of patients are bed bound, so staff will sit them up, sorting out toileting and so on. Following breakfast,
patients are washed and beds are changed. Beds are often moved around at this time in readiness
for admissions and discharges.
Doctors begin ward rounds at around 10.00; these continue throughout the morning and into mid
afternoon.
Drug rounds and patient observations continue throughout the day at noon, 17.30 and 21.00.
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The night shift changeover takes place at 19.15, and, as with the morning shift, a handover takes
place at the bedside. This is followed by patient observations and staff settling patients down for the
night. The ward lights are finally dimmed at around 22.30.
Meal times
A cold breakfast is served by the ward domestic staff at 08.30, followed by a separate hot drinks
trolley.
Lunch is served at midday, with the food arriving on a heated trolley and subsequently plated up in
the ward corridor, next to the nurse station. Meals are taken round to patients on a smaller trolley and
are served by the ward domestic staff. This is followed by a separate hot drinks trolley.
Afternoon hot drinks are served at 15.00, followed by the evening meal and hot drinks at 18.00.
Visiting times
Visiting times are strictly adhered to in this ward, except for terminally ill patients. Visiting time is split
to allow patients to eat their evening meal without disturbance. The hours are from 14.30 until 17.00,
and 19.00 until 20.30.
Sources of noise on the ward
The following were considered to be the main sources of noise:
Daily facilitator meeting
This meeting is held each day at 09.15 by the shift co-ordinator at the ward scheduling board next to
the nurse station. All staff attend this meeting which generally lasts for 30 minutes. This is a potential
source of noise to those female patients in the opposite 4-bed bay.
Nurse station
Noise levels at the nurse station are felt to be high, with one staff member commenting that there are
often multiple conversations taking place and that it is sometimes difficult to hear what is being said
on the telephone.
Telephone
There are two telephones at the nurse station. The ward manager feels that they ring incessantly,
especially during the morning.
Doorbell
This is answered by the ward clerk during working hours; otherwise it is answered by the nursing staff
at the nurse station.
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Patientline
This system is available here at a cost. Headphones are provided but are often not used.
Mobile phones
The ward manager considers the phone charges levied by ‘Patientline’ to be exorbitant and is
therefore lenient towards the use of mobile phones on the ward.
Equipment
Due to the nature of patient care on this ward, there are a number of pieces of medical equipment that
are in use. Ventilators, pumps and vital signs equipment are all common here.
Nurse call & emergency call
These systems are set on the night time level at all times, and are felt to be ineffectual in terms of
design.
The ward manager feels that the nurse call system on the ward is poorly designed, as busy staff are
often unaware that it has been activated. For example, if a patient in 4-bed bay A presses the nurse
call bell, a tone is emitted in this bay, with the occurrence shown on a display panel in this bay and at
the nurse station. A light is also displayed outside the bay in the corridor. However, this occurrence is
not shown on the display panels in any other patient accommodation, so if nursing staff are all busy
out on the ward, they are not necessarily aware that the nurse call has been pressed. The ward
manager feels that all occurrences of nurse call should be shown on all screens in all bays.
Each time the nurse call is activated, a tone is emitted in the ward manager’s office, which cannot be
cancelled or changed in volume. This is extremely annoying to the ward manager who finds that the
nurse call constantly sounding has a negative impact on her work. As the person responsible for
overseeing the running of the entire ward, she does not consider it necessary to hear every
occurrence of the nurse call, preferring instead to only be able to hear the emergency call bell, which
signifies a more serious event. The ward manager also commented that the emergency call bell was
ineffectual as it could not be heard throughout the ward and considered that a remote paging system
or similar would be preferable to the current systems.
9.5.4. Managing the study
The ward manager was supportive of the study and spent time ensuring that ward routines and
systems were understood. There were no undue concerns regarding the cleaning of the equipment
and the proposed microphone positions were acceptable. For comparison purposes it was considered
important that the microphone was placed in similar locations in each accommodation type. The
microphone positions are shown on the ward plan in Figure 9.11.
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As in previous locations, a 300 mm ceiling bracket was used to suspend the microphone from the
ceiling grid. The environmental case housing the SLM was positioned so as to minimise the risk of
theft and its impact on staff duties and patient care. In the patient bays the case was placed under a
section of worktop, and in the single rooms it was positioned behind an easy chair.
The distribution of patient questionnaires was not as straight forward as in previous study wards.
Patients who were bed bound and suffering from respiratory conditions were not considered to be fit
enough to complete the questionnaire. Only those patients who were able to get up and walk down to
the day room would be approached by the ward clerk (whose desk was opposite this room). This
meant that the number of patient questionnaires completed during the study period was low (n=13).
Laminated posters were displayed throughout the ward common areas explaining the study, and it
was hoped that staff would be informed of the research during staff meetings. Unfortunately, this was
not the case, and many of the staff approached during the study period had no knowledge of the work
being carried out. Questionnaires were left for completion in the staff room, however only a relatively
small amount were completed by the staff (n=10).
Figure 9.11 Detailed plan of the ward N3 showing microphone positions
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9.6. Overall acoustic survey results Ward N3
Noise level measurements were made at six different locations on the ward. Table 9.5 shows the
locations and the time periods of all measurements made, and the patient genders where applicable.
Table 9.5 Measurement location, time interval and patient type
Position Length of measurement period Patient gender
Nurse Station 5 days N/A
4-bed bay A 7 days Male
4-bed bay B 8 days Female (special care)
4-bed bay C 7 days Female
Single room J 7 days Male / Female
Single room K 9 days Male / Female
Overall measurements of A-weighted equivalent sound pressure levels (LAeq) were averaged and are
shown for 24 hours, day time and night time in Table 9.6.
Table 9.6 Average LAeq measured for 24 hour, day and night time periods at each location.
Position in ward Week average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Nurse Station 51.7 53.4 47.4
4-Bed Bay A 50.9 52.3 44.6
4-Bed Bay B 52.1 53.3 47.2
4-Bed Bay C 48.8 50.0 44.3
Single Room J 49.3 50.6 43.6
Single Room K 51.1 52.5 45.1
A summary of the day and night time average levels presented in Table 9.6 are presented graphically
in Figure 9.12 for clarity. As with the wards at Bedford Hospital, noise levels in all patient
accommodation exceed those suggested in the WHO guidelines. It can also be seen that all average
day and night time levels measured in the patient accommodation were very similar, within a 3.3 dB
range from 50.0 to 53.3 dB LAeq, 16hr during the day and 3.6 dB range from 43.6 to 47.2 dB LAeq, 8hr at
night. Interestingly, the nurse station on this ward has comparable noise levels to those shown in most
of the patient accommodation.
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The day to night drop in levels is fairly consistent, with an average drop of 7 dB in the patient
accommodation and a smaller drop of 5 dB at the nurse station. This is comparable with nurse
stations on the study wards at Bedford Hospital and Ward D8.
The highest day and night time levels were measured in 4-bed bay B, the special respiratory care
unit. This is unsurprising given the amount of respiratory equipment in use on this bay.
0
10
20
30
40
50
60
70
Nurses Station 4-Bed Bay A 4-Bed Bay B 4-Bed Bay C Single Room J Single Room K
So
un
d P
res
su
re (d
B L
Aeq
,1h
r)
Day
Night
Figure 9.12 Average day and night LAeq levels measured at each location
Detailed results of levels measured at the nurse station are discussed in the next section, with further
results from the multi-bed bays shown in Section 9.6.2 and levels measured in the single rooms in
Section 9.6.3.
9.6.1. Nurse station
Figure 9.13 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station. The
figure shows that noise levels are very steady during the night, from around 21.30 until 05.00, after
which they climb to a temporary peak during the daily facilitator meeting at around 09.30. Other small
peaks can be observed at lunch time, dinner time and during evening shift changeover. The
measured LA90,1hr levels provide a good indication of the variation in background noise levels over
time, with night time background levels remaining very constant at around 39 dB LA90, and day time
background levels peaking at lunch time at around 45 dB LA90.
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20
30
40
50
60
70
So
un
d P
res
su
re (d
B L
Aeq
,1h
r)
Time (24h:00)
Nurse station LAeq Nurse station LA90
Night time
Day time
Figure 9.13 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station
To illustrate the fluctuating nature of noise in the short term, Figure 9.14 shows noise levels captured
at the nurse station over a 13 minute time interval during the afternoon, with the microphone
approximately 2 m away from the main desk area. Certain high level noise events with LAmax greater
than 70 dB have been identified.
Figure 9.14 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 13 minute interval at the
nurse station during the afternoon
A number of rooms are situated close to the nurse station, including the clean and dirty utility rooms,
and a storeroom. All doors to these areas have security access via a key code pad. Staff often have
their hands full when entering or leaving these rooms, and so the doors to these rooms are generally
left on the latch, avoiding the need to input the security code and making the doors easier to push
open. Unfortunately, this has the adverse effect that the door literally bounces when it shuts, causing
a loud noise. This is a good example of the ward not being used as its designer intended and is
RING
BINDERS BANGING DOORS
BANGING DOOR
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further illustrated by Figure 9.15, which shows the 1/3 octave band frequency spectrum of a typical
door bang. Banging doors accounted for 48% of the total number trigger files captured during the
measurement period in this location.
The acoustic ceiling tiles installed throughout the ward are optimal at speech frequencies. The
frequency content of the banging door shown in Figure 9.15 is clearly biased towards low frequencies.
This is a good illustration of the type of high level noise for which current levels of absorbency may
not be so effective.
Figure 9.15 Frequency content of door bang at the nurse station
As in other study wards, the use of ring binders also caused a relatively high number of trigger files at
the nurse station (8% of the total number captured during the measurement period). All patient
records are kept in ring binders, along with other reference materials, and often are the main source
of late night noise, when the staff are catching up with administrative work.
To further illustrate the types and noise levels of typical high level events at the nurse station,
examples are presented in Table 9.7. It should be noted that the levels shown are for individual
events and may not be representative of every noise event of that type.
Table 9.7 Examples of noise events at the nurse station
Noise event LAmax (dB)
Doors banging 77; 79
Ring binder 72
Trolley 77
Footsteps 71
Unusually, footsteps are a source of high level noise at the nurse station. This is caused by groups of
people walking past the microphone, and not a single person, which would not be sufficiently loud.
However, the fact that footfall is responsible for noise levels exceeding 70 dB LAmax indicates a
potential issue with the timber floor and its vinyl covering. This is confirmed by the questionnaire
responses in which 40% of ward staff found the sound of footsteps annoying, and 20% of patients
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cited footsteps as a cause of night time disturbance. These percentages are the highest found in
relation to annoyance and disturbance from footsteps on any study ward.
Unlike other study wards the internal telephone, nurse call and doorbell were not set at levels which
were loud enough to create trigger files at the nurse station, however this did not prevent these
systems from causing annoyance and interference to staff, as can be seen in Section 9.9, and
suggests that noise annoyance is not related to noise level alone.
9.6.2. Multi-bed bays
Figure 9.16 shows the averaged LAeq,1hr levels over 24 hours for the three 4-bed bays and the average
background level (LA90,1hr) of all bays. It can be seen that the levels measured in the male and female
bay are reasonably consistent, with the male bay appearing slightly noisier during the day and the
female bay slightly noisier at night. Measured levels in the special respiratory care unit are
consistently higher than in the other two bays. The reasons for this are investigated further in Section
9.6.4. The average background level varies from around 38 dB LA90 during the night to 42 dB LA90
during the day; these levels are slightly lower than those measured at the nurse station.
Levels appear to follow ward routines to some degree, with the levels rising steadily after the main
lights are switched on just after 07.00, and temporarily peaking at the end of the staff daily meeting,
when nursing staff and doctors return to the wards for the ward rounds. Levels peak again around
lunch time. After lunch levels in the respiratory care unit remain fairly stable until around 23.00, but
levels in bays A and C can be seen to fluctuate slightly more, with a peak around 18.30 in bay A. This
may be related to the serving of the evening meal.
20
30
40
50
60
70
So
un
d P
ressu
re (
dB
LA
eq
,1h
r)
Time (24h:00)
4 Bed Bay A (Male) 4 Bed Bay B (Special Respiratory Care) 4 Bed Bay C (Female) Average LA90
Night time Day time
WHO GUIDELINES
Figure 9.16 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level for all bays
over 24 hours
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Figure 9.16 also shows that the WHO day / night division is not a particularly good fit. Noise levels
increase steadily from around 06.00 rather than 07.00, and begin to decrease after the evening meal
is served. This suggests it might be appropriate to redefine the ‘day’ and ‘night’ time periods for
hospital noise assessment.
9.6.3. Single patient rooms
Figure 9.17 shows the average LAeq,1hr levels over 24 hours in the two single rooms measured. The
average level from the three multi-bed bays is also shown for comparison purposes. It can be seen
that levels for single room J are consistently lower than the average of the multi-bed bays, and noise
levels measured in single room K are similar to the multi-bed average. It is also noticeable that the
effects of the ward routines on the measured levels appear to be much less pronounced in the single
rooms.
20
30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
,1h
r)
Time (24h:00)
Single Room J Single Room K Mean 4-Bed Bays
Night time Day time
WHO GUIDELINES
Figure 9.17 Average LAeq,1hr levels over 24 hours for the single rooms
The day time measured LAeq,16hr for single room J is lower than for any other single room measured in
any of the study wards. This was in part due to the patient, who was elderly, unable to speak well due
to his respiratory problems, slept a great deal and received few visitors. In this instance, patient
procedures accounted for the highest percentage of high level noise events, including doctor’s visits,
nurses’ observations, and patient washing and changing. This patient was bedridden and so required
a high level of care. Medical equipment alarms, when they were activated, were typically no louder
than 57 dB LAmax.
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The occupant of single room K had a very bad cough, but was well enough to talk to staff and
received more visitors than the patient in room J. High level coughing, clinical activity and
conversation accounted for the higher noise levels in this single room.
9.6.4. Further analysis of high level noise sources
To help build up a further picture of the sources of high level noise at each location, the numbers of
occurrences of LAmax in 5dB bands from 70 to 95 dB have been examined. Figures 9.18 and 9.19
show the average number of high level noise events during the day and night in different
measurement locations.
0
50
100
150
200
250
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 9.18 Average number of high level noise events recorded at each location per day
It can be seen that 4-bed bays A and B show the largest numbers of high level noise events during
the day, with 4-bed bay C registering much fewer. This highlights the limitations of simply viewing the
average LAeq,1hr levels, as shown in Section 9.6.2, which indicates similar levels between bays A and
C. The average number of day time high level noise events with an LAmax between 70 and 75 dB in
bay A is 100 higher than in bay C, suggesting some differences in the noise climate.
To explain some of the differences between bays in terms of high level noise, it was found that the
nurse call was responsible for 20% of trigger files captured during the seven day measurement period
in bay A, with each intermittent tone captured at an average level of 72 dB LAmax. However this was not
the case in bays B and C as here the nurse call did not generate any trigger files, only registering at
around 51 dB LAmax. Much of the high level noise generated in bay B fell into the ‘unidentifiable’
category, suggesting more clinical activity in this bay. Conversation and administrative tasks at the
integral nurse station also added to these noise sources.
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It can also be seen in Figure 9.18 that, unusually, the nurse station has more high level noise events
with LAmax between 75 and 80 dB, than those with LAmax between 70 and 75 dB. As discussed in
Section 9.6.1, this is largely due to the banging doors, which are measured at consistent levels in this
range.
Figure 9.19 shows the night time average number of high level noise events recorded at each location.
In this case it is the nurse station and bay B which show the highest numbers of events. As with the
day time noise, the nurse station is affected by doors banging, and other sources of high level noise
are mostly generated by administrative activity, especially the use of ring binders.
0
5
10
15
20
25
30
35
40
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y c
ate
go
ry
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 9.19 Average number of high level noise events recorded at each location per night
As discussed previously, bay B also has its own integral nurse station, and it is this area where some
of the high level noise was generated. Figure 9.20 shows a further breakdown of night time noise in
bay B. It can be seen that patients coughing / sneezing / gurgling and groaning accounts for 45%
percentage of trigger files captured during the night. This is unsurprising as patients in this bay have
acute respiratory problems. Noise due to administrative tasks carried out at the integral nurse desk
accounts for 35% of trigger files; which suggests that patients may be disturbed by activity in this area
during the night.
0 5 10 15 20 25 30 35 40 45 50
Unidentifiable
Cough / sneeze / gurgling / groaning
Furniture scraping
Ring binder / admin at nurses' desk
Cupboard door / drawers
Bathroom door
% of high level noise sources (LAmax > 70 dB)
Figure 9.20 Percentage break down of high level noise events by type in 4-bed bay B
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9.7. Ward M4 (surgical)
The Addenbrooke’s Treatment Centre (ATC) was opened in November 2007 at a cost of £84 million.
This building was built under the PFI (Private Finance Initiative) scheme and houses operating
theatres and wards for emergency surgery, a new endoscopy suite, and facilities for all inpatient
gynaecology, urology and breast surgery services. Ward M4 is situated on the 4th
floor of the ATC and
is a surgical ward specialising in urology. The ward has a total of 32 beds, divided between five 4-bed
bays and 12 single rooms, and is predominantly male. Women admitted for treatment on this ward
tend to be put into a single room. 60% of admissions are elective (through a GP) and 40% of
admissions are emergencies. Ward admissions can be at any time during the day and night, with 60%
of patients arriving on the ward on the day of their procedure.
9.7.1. Building construction
The construction of the ATC building is primarily concrete, double glazed and mechanically ventilated.
Built to comply with acoustic standard HTM 2045, the suspended ceiling grid is fitted with acoustic
tiles with good absorption properties; the plasterboard stud walls are sound insulated; and the 1 m
thick reinforced concrete floor is covered with heavy duty vinyl.
9.7.2. Ward layout
A number of senior staff offices and meeting rooms are positioned just before the ward entrance,
which requires card access. The ward is laid out on both sides of a long straight corridor, with the
patient accommodation located on the outer wall of the building, making best use of the natural light
and views over the countryside. All patient rooms have ensuite bathroom facilities. Healthcare utilities
are situated in the centre of the building (on the left of the corridor when walking from the entrance).
Some of these utilities, for example the clean and dirty utility rooms, larger storerooms, larger offices,
and the lifts used for patient transport, are shared with another ward which runs parallel to M4, as
shown in Figure 9.21 on page 179.
There are three nurse stations on the ward, one at the entrance, one halfway down the ward and one
at the end of the corridor. The ward manager felt that the central nurse station and the one closest to
the entrance were likely to be the noisiest, and so for this reason these areas were chosen for
measurement.
The ward is designed so that single rooms are positioned in pairs, and due to the location of the
ensuite facilities, the rooms are set back, allowing patients in these rooms to be further away from
well trafficked corridor areas. This can be seen in Figures 9.21 and 9.22 on pages 179 and 180
respectively. The 4-bed bays open directly out onto the main corridor.
The ward corridors and patient accommodation have a spacious and uncluttered feel, and as
discussed in Section 9.3.1, the ward area is large (1250 m2
with 28 patients) compared to ward D8
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(850 m2 with 35 patients). Single rooms have a floor area of approx 18 m
2 and 4-bed bays have a
floor area of approx 53 m2.
9.7.3. Ward specific information
Doors
The ward manager prefers all doors to patient accommodation to be left open at all times to allow the
nursing staff to monitor the patients. If a patient falls or gets into difficulties the nursing staff can either
see or hear. Even in rooms where patient barrier nursing is required, doors are still left open. In
general, the only exception is when a patient is nearly fully recovered and waiting to go home.
MRSA
All patients are swabbed for MRSA on admittance and if the results are positive they are generally
placed in a single room. Prior to the swab result being received, the patients are placed in a room with
others whose results are not yet known. Patients are often moved to different locations on the ward
during their stay.
Occupancy levels
During the week the ward runs at 100% occupancy. During the weekend (from Friday evening until
Sunday evening) five beds should be closed, however, it appears that this is a rare occurrence. Bay
23 is always fully occupied as this is closest to the nurse station and therefore is good from an
observation point of view.
Staffing levels and shift patterns
Staffing levels from 07.15 until 19.15 are the highest, with seven staff nurses and three healthcare
assistants. This reduces to six nursing staff during the night shift, from 19.15 until 07.15. Other staff
include three cleaners, two ward assistants and a ward clerk. During weekends there are slightly
fewer staff with six staff nurses and one healthcare assistant.
Ward routines
The first patient visits begin at 06.00 for general observations, including temperature, bloods and
urine samples. New admissions begin to arrive on the ward at 07.00.
Morning shift handover takes place in the seminar room between 07.15 and 07.45 and is immediately
followed by a drug round.
The first theatre admissions begin at 08.00, with two sets of porters collecting and returning patients
to and from theatre. This continues throughout the day. At this time there is a great deal of noise at
the nurse station with doctors checking the admissions board and bed managers arriving on the ward.
Doctors begin their ward rounds at this time.
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At 10.30 the phlebotomists arrive on the ward with two trolleys to collect bloods, this is followed by
further drug rounds and general observations which are carried out at 12.30, 17.00 and 21.00.
Doctors pay post-operative visits to patients at 18.00 and the night shift handover takes place
following this, between 19.15 and 19.45 in the seminar room.
The main ward lights are turned out at 22.30.
Meal times
Breakfast and coffee is served by ward assistants on trolleys between 07.45 and 08.30. This is
followed by a mid morning tea round at 10.00.
Lunch is served at 12.00, followed by a tea round, with food delivered to the ward in a large ‘hot’
trolley. Meals are plated up and taken to the patients by hand by two ward assistants and a
healthcare assistant. Unlike Bedford Hospital, mealtimes are not ‘protected’ on this ward and patients
may still be undergoing CT scans or being taken to and from surgery during the serving of meals.
There is a further tea round at 15.00, followed by a light supper at 17.00. The final tea round is at
20.00.
Deliveries
Fresh linen is delivered to the ward on a daily basis, at 09.00. The linen is delivered in a large cage
which is taken from the lift lobby to the central nurse station and swapped for the dirty linen trolley.
Thursday is the main day for ward deliveries, with items brought up to the ward in large cages after
lunch.
Visiting times
The official hours for visiting time are 14.00 until 20.00.
Sources of noise on the ward
The following are thought to be the main sources of noise:
Doorbell
The entrance to the ward is through a security door, which has a doorbell, the use of which peaks
during visiting time.
Cleaning
Cleaning begins in the morning and continues throughout the day and comprises of dusting and
mopping the floor. Full floor buffing takes place on a weekly basis. Bins are changed twice daily (more
if required).
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Doors
Fire doors are heavy and tend to slam loudly.
Nurse Call
Telephone
There are 3 telephones on the ward. The ward manager felt that during busy times the phones ring
endlessly as there is no member of staff free to answer them. A cordless phone was tried as an
alternative, but this was not entirely successful and was eventually lost.
Patientline
This system is available here at a cost. Headphones are provided but are not always used.
Portable DVD players
Patients sometimes bring these in to watch their own DVDs.
Mobile Phones
To avoid setting a precedent, even the doctors tend to go out into the hallway to use their mobile
phones.
9.7.4. Managing the study
The ward manager was supportive of the study and spent time ensuring that ward routines were
understood. Particular interest was expressed in measuring noise levels at two of the nurse stations
for comparison purposes, as it was suspected that the central station was adversely affected by noise
from the nearby lifts, and had become a congregation point for staff. Both areas were incorporated
into the study.
Two four bed bays and two single patient rooms were identified as suitable study locations with input
from the ward manager. For each accommodation type, similar positions were found for the
microphone, which was suspended from the ceiling grid using a 300 mm ceiling bracket. The
environmental case housing the SLM was positioned so as to minimise the risk of theft and its impact
on staff duties and patient care. In the patient bays the case was placed on a section of worktop, and
in the single rooms it was positioned behind an easy chair. A ward plan showing these positions can
be seen in Figures 9.21 and 9.22.
Although the ward clerk was tasked with passing the questionnaires to patients who had been on the
ward for over 24 hours and were deemed fit enough to complete the questionnaire, this was not as
successful as in other study wards. The role of ward clerk rotated between a number of staff and so
the questionnaires were often forgotten; with only 14 completed questionnaires collected.
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Laminated posters were displayed throughout the ward common areas explaining the study, and it
was hoped that staff would be informed of the research during staff meetings. Unfortunately, this was
not the case, and many of the staff approached during the study period had no knowledge of the work
being carried out. Questionnaires were left for completion at the nurse station, and a box was
provided for completed questionnaires, however only a relatively small number (10) were completed
by the staff.
Figure 9.21 Plan of Ward M4 detailing shared areas and microphone positions
Figure 9.22 Detailed plan of Ward M4 showing study locations and microphone positions
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9.8. Overall acoustic survey results Ward M4
Noise level measurements were made at six different locations on the ward. Table 9.8 shows the
locations and the time periods of all measurements made, and the patient genders where applicable.
Table 9.8 Measurement location, time interval and patient gender
Position Length of measurement period Patient gender
Nurse station 1 5 days N/A
Nurse station 2 7 days N/A
4-bed bay A 6 days Male
4-bed bay B 8 days Male
Single room A 7 days Female
Single room B 9 days Male / Female
Overall measurements of A-weighted equivalent sound pressure levels (LAeq) were averaged and are
shown for 24 hours, day time and night time in Table 9.9.
Table 9.9 Average LAeq measured for 24 hour, day and night time periods at each location
Position in ward Week average of A-weighted equivalent sound pressure levels
24 hours Day time Night time
LAeq, 24hr LAeq, 16hr LAeq, 8hr
Nurse Station 1 56.4 55.1 48.1
Nurse Station 2 52.2 53.6 46.7
4-Bed Bay A 50.6 52.7 43.0
4-Bed Bay B 52.4 54.0 43.4
Single Room A 50.9 52.3 42.1
Single Room B 53.2 53.5 49.1
A summary of the day and night time average levels presented in Table 9.9 are presented graphically
in Figure 9.23 for clarity. As with the wards at Bedford Hospital, noise levels in all patient
accommodation exceed those suggested in the WHO guidelines without exception. It can also be
seen that all average day time levels measured in the patient accommodation were very similar,
within a 1.7 dB range from 52.3 to 54.0 dB LAeq, 16hr. Night time levels were also very consistent with a
1.3 dB range from 42.1to 43.4 dB LAeq, 8hr, with the exception of single room B which had a much
higher average of 49.1 dB LAeq, 8hr . Day to night drop was also fairly consistent with an average drop of
10.2 dB in patient accommodation, with the exception of single room B which had an average drop of
just 4.4 dB.
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As the ward manager suspected, noise levels were higher at the central nurse station (nurse station
1), however the differences between the nurse stations were very small, with a 1.5 dB difference in
average levels during the day and 1.4 dB difference at night. Further analysis is necessary to
understand the level fluctuations and sources of high level noise in these two cases, which are
discussed in Sections 9.8.1 and 9.8.4. Results from the multi-bed bays and single rooms are
presented in Sections 9.8.2 and 9.8.3 respectively.
0
10
20
30
40
50
60
70
Nurse Station 1 Nurse Station 2 4-Bed Bay A 4-Bed Bay B Single Room A Single Room B
So
un
d P
ressu
re (
dB
A)
Day
Night
Figure 9.23 Average day and night LAeq levels measured at each location
9.8.1. Nurse stations
Figure 9.24, shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the two nurse stations.
The figure shows that noise levels at Nurse Station 1 (NS1) are consistently higher than those
measured at Nurse Station 2 (NS2) during the day and then converge at around 21.00 for four hours.
Levels at NS2 are again consistently lower from 01.00 until 05.00, suggesting less activity in the area
at this time.
Average levels at NS1 show several peaks in line with the ward routines. Levels rise to an initial high
at around 08.00, when the doctors and bed managers arrive at the nurse station to check the day’s
schedules. Another peak can be seen around lunch time and then, as suspected by the ward
manager there is a peak at the end of the day shift.
Background levels during the night are around 37 LA90,8hr, and provide a good indication of the overall
building services noise.
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20
30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
,1h
r)
Time (24h:00)
LAeq Nurse Station 1 LAeq Nurse Station 2 LA90 Nurse Station 1 LA90 Nurse Station 2
Night timeDay time
Figure 9.24 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations
Figure 9.25 shows noise levels captured at NS2 over a 15 minute time interval at 05.30 in the
morning, with the microphone approximately 2 m away from the main desk area. Using the trigger
files captured when LAmax exceeds 70 dB, certain high level noise events have been identified.
Figure 9.25 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 15 minute interval at the
nurse station at 05.30
The door to the dirty utility room is situated behind NS2 and each time the door closes it generates a
noise with an LAmax of 72 dB. This room is used a great deal and is responsible for many trigger files,
both day and night. Other sources of night time noise at this nurse station are generally related to
administrative tasks and include ring binders, and desk drawers banging shut. High level noise events
during the day are similar, with more high level conversation and noise from corridor traffic, such as
trolleys.
BANGING DESK
DRAWERS
CLOSING DOOR CLOSING DOORS
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High level noise events captured at NS1 are generated in the main by high levels of conversation.
This nurse station is larger than NS2 and many more staff congregate here. As with NS2,
administrative tasks are also responsible for some high level noise events, with a ring binder captured
at 83 dB LAmax. Interestingly, although the nurse call, doorbell and internal telephone are all cited by
staff in this ward as annoying and interfering with their ability to carry out their jobs effectively (see
Section 9.9.1), none of these systems is loud enough to generate high level noise events, that is LAmax
greater than 70 dB.
9.8.2. Multi-bed bays
Figure 9.26 shows the averaged LAeq,1hr and background levels (LA90,1hr) levels over 24 hours for the
two 4-bed bays. It can be seen that the levels measured in bays A and B are reasonably consistent,
with bay B appearing slightly noisier during the main part of the day. The average background level in
bay B is consistently lower at night, at around 32 dB LA90, with bay A around 35 dB LA90. An
explanation for these differing levels could be the proximity of the main nurse station. Bay A is
opposite the ward lifts and close to NS1, whereas bay B is opposite an aided bathroom and store,
which would be little used at night. As discussed previously doors to the multi-bed bays are left open
at all times, and thus noise from the ward lifts and NS1 may affect background levels.
20
30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
,1h
r)
Time (24h:00)
LAeq 4-Bed Bay A LAeq 4-Bed Bay B LA90 4-Bed Bay A LA90 4-Bed Bay B
Night time Day time
WHO GUIDELINES
Figure 9.26 Average LAeq,1hr and LA90,1hr level for each multi-bed bay over 24 hours
Levels appear to follow ward routines to some degree, with the levels rising steadily at around 06.00,
when the first observation round begins. At around 08.00, when the doctors arrive on the ward and
theatre admissions begin, levels increase sharply. A small dip can be seen just before the start of
visiting time, with levels decreasing slowly after the evening meal is served.
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Figure 9.26 also shows that the WHO day / night division is not a particularly good fit. As discussed,
noise levels increase steadily from around 06.00 rather than 07.00, and begin to decrease after the
evening meal is served. This suggests it might be appropriate to redefine the ‘day’ and ‘night’ time
periods for hospital noise assessment.
The microphone situated in the multi-bed bays was suspended from the ceiling in the corner of the
room close to the entrance doors. In both bays this was over a small worktop area, where there was
also a rubbish bin, plastic apron and glove dispenser, sink and some hospital wheeled equipment
stored. To avoid any coloration of results due to the use of the sink and bin, this location was chosen
in both bays, to allow for comparisons. Further discussion of high level noise can be found in Section
9.8.4.
9.8.3. Single patient rooms
Figure 9.27 shows the average LAeq,1hr levels over 24 hours in the two single rooms measured. The
average level from the two multi-bed bays is also shown for comparison purposes. It can be seen that
at night, levels for single room A are consistently lower than the average level of the multi bed bays
and levels for single room B are consistently higher than this average. During the day all levels are
comparable, following similar patterns of fluctuation
20
30
40
50
60
70
So
un
d P
ressu
re (
LA
eq
,1h
r)
Time (24h:00)
LAeq Single Room A LAeq Single Room B Mean LAeq 4-Bed Bays LA90 Single Room A LA90 Single Room B
Night time Day time
Figure 9.27 Average LAeq,1hr and LA90,1hr levels over 24 hours for the single rooms
Single room A is situated opposite the main nurse station; the internal phone ringing and staff talking
loudly and laughing can often be heard in the background when reviewing trigger files of high level
noise events inside this room. However, it is assumed that the door to this room is shut at night,
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resulting in the extremely low background noise levels measured, at around 24 dB LA90. These are the
lowest background levels measured in any study ward.
During the measurement period there were three different patients occupying single room A. All were
female, and relatively quiet. Sources of high level noise were routinely caused by room cleaning, bin
bag changing and use of the rubbish bin, which was captured at a level of 81 dB LAmax. Visits by
clinicians and the serving of meals also accounted for a percentage of high level noise, with domestic
staff talking to the patients unnecessarily loudly at times.
The patients in single room B during the measurement period were male, with sources of high level
noise found to be similar to those in room A. Additional high level events were the closing of the room
door, measured at around 78 dB LAmax, and persistent coughing of the second patient staying in the
room at levels up to 79 dB LAmax. Night time LAeq levels in this room were on average 7 dB higher than
those measured in single room A, with background levels around 13 dB higher. It is thought this was
due to the constant use of a portable cooling fan and some low level alarms of the monitoring
equipment in this room.
9.8.4. Further analysis of high level noise sources
To help build up a wider picture of the sources of high level noise at each location, the numbers of
occurrences of LAmax in 5 dB bands from 70 to 95 dB have been examined. Figures 9.28 and 9.29
show the average number of high level noise events during the day and night in different
measurement locations.
It can be seen that the main nurse station (NS1) accounts for the majority of high level noise events,
with an average of over 450 events during the day between 70 and 75 dB LAmax. As already
discussed, much of this is due to high level conversation between staff, and some administrative
tasks. Much of the high level noise at NS2 is due to the banging shut of the door to the dirty utility
room; the effect of this which may be to build up an artificially high picture of noise levels in this area.
4-bed bay B shows the largest numbers of high level noise events measured in a multi-bed bay during
the day, with 4-bed bay A registering much fewer. Here, the specific difference appears to be primarily
due to a patient with a loud and persistent cough in bay B. All other high level events are similar, with
the use of the rubbish bin, plastic apron and glove dispenser and sink noticeable in both bays. A loud
bang is consistently captured as the lid of the rubbish bin lid closes, measured at an average level of
83 dB LAmax. With the nearest patient in a bed only a short distance away from this bin, this may cause
annoyance. Although not loud enough to create a trigger file, music can sometimes be heard in the
background of trigger files captured in the bays. This is substantiated by a patient comment made
regarding the use of radios and TVs without enforcing the use of headphones.
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0
50
100
150
200
250
300
350
400
450
500
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
90 ≤ LAmax < 95 dB
Figure 9.28 Average number of high level noise events recorded at each location per day
Figure 9.29 shows the night time average number of high level noise events recorded at each location.
In this case it is NS2, NS1 and single room B respectively which show the highest numbers of events.
As with the day time noise, NS2 is affected by the door of the dirty utility room banging, whereas the
majority of high level noise at NS1 is caused by high levels of conversation and administrative tasks.
As discussed previously, there was a patient in single room B with a loud, persistent cough that
accounts for the numbers of high level noise sources captured during the night.
0
10
20
30
40
50
Nu
mb
er
of
reco
rde
d n
ois
e e
ven
ts b
y ca
teg
ory
70 ≤ LAmax < 75 dB
75 ≤ LAmax < 80 dB
80 ≤ LAmax < 85dB
85 ≤ LAmax < 90dB
Figure 9.29 Average number of high level noise events recorded at each location per night
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9.9. Results of the staff questionnaire surveys
The design of the questionnaire surveys was discussed in detail in Section 5.4.
Staff response was good in Ward D8 with 21 questionnaires completed, but response rate in the other
wards was low, with only 10 staff completing the survey in wards N3 and M4.
The following sections discuss results from the staff questionnaires and examine the differences
between perceptions on the three wards.
9.9.1. Staff profile
To establish certain attributes about the staff, the first section posed a number of basic questions. Out
of all the respondents, 73% were female and 27% male, with similar percentages in all three wards.
Figure 9.30 shows the ages of the respondents. It can be seen that in all wards the respondents were
generally younger than 50, with a higher percentage of young staff members completing the
questionnaire in wards D8 and N3.
0 20 40 60 80 100
Less than 20
20-30
31-40
41-50
51-60
60+
Percentage of respondents
Ag
e b
an
d (
ye
ars
)
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.30 Age of respondents by band
The length of time worked both on the wards and at the hospital are shown in Figures 9.31 and 9.32
respectively, which suggest that many of the staff have worked at the hospital for longer than they
have worked on their specific ward.
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0 10 20 30 40 50 60 70
< 1 year
1- 2 years
2 - 3 years
3-4 years
4-5 years
5+ years
Percentage of respondents
Tim
e w
ork
ed
on
th
e w
ard D8 (n=21)
N3 (n=10)
M4 (n=10)
0 10 20 30 40 50
< 1 year
1- 2 years
2 - 3 years
3-4 years
4-5 years
5+ years
Percentage of respondents
Tim
e w
ork
ed
at
the
ho
spit
al
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.31 Time worked on the ward Figure 9.32 Time worked at the hospital
9.9.2. Noise annoyance
General feelings of noise annoyance were investigated by asking staff to what extent they were
annoyed by noise. Figure 9.33 shows that the highest percentages of staff on all wards were ‘slightly’
annoyed by noise. Ward D8 shows the most diverse response, with some staff indicating ‘not at all’
annoyed and a small proportion choosing ‘extremely’ annoyed.
0 20 40 60 80 100
Not at all
Slightly
Moderately
Very much
Extremely
Percentage of respondents
Sta
ff p
erc
ep
tio
n o
f n
ois
e a
nn
oy
an
ce
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.33 Staff perception of noise in terms of annoyance
Staff were asked to rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating
‘not at all annoying’ and 4 indicating ‘a great deal’. Figure 9.34 shows the percentages of staff who
rated a noise event with a 2, 3 or 4, and so could be said to be more than a little annoyed by the
event.
It can be seen that the four events rated by a high percentage of staff in Ward M4 were the doorbell
(80%), internal telephone (70%), medical equipment alarms (60%), and the nurse call (60%). Staff in
wards N3 and D8 also rated these events, but the percentage of those annoyed by the internal
telephone, nurse call and medical equipment alarms was 10 - 20% lower. The doorbell was not a
major source of annoyance on wards N3 and D8.
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Other events cited by 30% or more staff on the wards were people talking, and staff talking on the
telephone. Visiting time; the talking on and ringing of mobile phones; and TV / radio use were all rated
more highly in wards D8 and N3 than M4. This maybe an indication of a more lenient approach by
ward staff.
Some anomalies can be seen in Figure 9.34. Trolleys, footsteps, rubbish bins and external noise were
all cited as annoying by 40% of respondents in N3, but much less so (or not at all) in the other wards.
The timber floor construction of N3 is thought to increase the noise of trolleys and footsteps in this
ward, as discussed in Section 9.5.1. External noise annoyance may have been exacerbated as the
study was carried out during warmer weather in this ward and so more windows may have been open
at the time of the survey.
0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
Nurse call
Doorbell
Footsteps
Medical Equipment
People talking
Cleaning
Rubbish bins
Trolleys
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Visiting time
% of staff rating annoyance event 2 or above
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4
9.9.3. Interference with work
Respondents were asked to what extent noise interfered with their ability to work effectively. As can
be seen in Figure 9.35, opinion of the respondents in all the wards was very split, with staff in ward D8
seemingly slightly more adversely affected by noise than in the other wards, with 33% choosing
‘moderately’.
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0 20 40 60 80 100
Not at all
Slightly
Moderately
Very much
Extremely
Percentage of respondents
Sta
ff p
erc
ep
tio
n o
f n
ois
e i
nte
rfe
ren
ce
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.35 Staff perception of the extent to which noise interferes with work
Staff were also asked to rate how much each noise event interfered with their ability to carry out their
job effectively (again the rating scale of 0 to 4 was used). Figure 9.36 shows the percentages of staff
who rated a noise event with a 2, 3 or 4, and so it could be said that this noise event interfered to
some extent with their ability to carry out their job effectively.
0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
Nurse call
Doorbell
Footsteps
Medical Equipment
People talking
Cleaning
Rubbish bins
Trolleys
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Visiting time
% of staff rating interference event 2 or above
D8 (n=21)
N3 (n=10)
M4 (n=10)
Figure 9.36 The percentages of staff rating an interference noise event with a 2, 3 or 4
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It can be seen that the numbers of staff rating events as interfering with their work are generally fewer
than for annoyance. However, the internal telephone is still consistently rated by 50% or more staff,
with visiting time and the nurse call both still rated by 30% or more respondents in each ward. Medical
equipment, which was rated as annoying by 50% or more, is rated less severely in the case of
interference, presumably as staff feel that they need to hear these alarms to make necessary
decisions.
There are several anomalies worth noting. TV / radio usage, trolleys, rubbish bins, footsteps, doors
banging and external noise are all rated by more staff in Ward N3. As mentioned in relation to
annoyance, some of these events may be exacerbated by the construction of the timber floor.
Banging doors has also shown to be a problem specifically in the area surrounding the nurse station
in this ward (see Section 9.6.1).
9.9.4. Important sounds
To aid understanding of which sounds were felt by staff to be important to be heard in order to carry
out their jobs effectively, staff were asked to rate different noise events on a scale of 0 to 4, where 0
indicated ‘not at all important’ and 4 indicated ‘extremely important’.
Figure 9.37 shows the mean ratings for each noise event. It can be seen that ‘patients calling out’
were considered by staff in all wards to be the most important noise event. However, the average
ratings were consistently high in all cases suggesting that all of these events are important for staff.
0
1
2
3
4
Nurse call Conversations
with colleagues
Conversations
with patients
Medical
equipment
alarms
Patients calling
out
Patient activity
D8 (n=20)
N3 (n=11)
M4 (n=10)
Figure 9.37 Mean importance rating of certain noise events
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9.10. Results of the patient questionnaires
With the help of the ward clerks, questionnaires were distributed to those patients who had been on
the ward for over 24 hours and were judged to be physically and mentally fit enough to complete the
survey. In total 74 patients completed the questionnaire: 47 in Ward D8; 13 in Ward N3; and 14 in
Ward M4.
The following sections discuss results from the patient questionnaires and examine the differences
between perceptions on the three wards.
9.10.1. Patient profiles
As with the staff questionnaire, the first section aimed to establish certain attributes about the
patients, beginning with the question of gender. As discussed previously, wards D8 and N3 are split
male / female wards and ward M4 is predominantly male. This is shown clearly in Figure 9.38 below:
0 20 40 60 80 100
Male
Female
Percentage (%)
D8 (n=47)
N3 (n=13)
M4 (n=14)
Figure 9.38 Gender split by ward type
Respondents were asked for their age range, and as shown in Figure 9.39, a high percentage of
patients were older, with 60% in the respiratory ward (N3), and 50% in wards D8 and M4 aged 60
years or above.
0 10 20 30 40 50 60 70
< 20
20-30
31-40
41-50
51-60
60+
Percentage (%)
Ag
e r
an
ge
D8 (n=47)
N3 (n=13)
M4 (n=14)
Figure 9.39 Patients age by band
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Respondents were asked how long they had been on the ward, and it can be seen in Figure 9.40 that
the majority had been on the ward for less than one week. Ward D8 shows the longest stay patients,
which is unsurprising due to the variety of conditions treated on this ward, with some patients
admitted for elective surgery and others on the ward as a result of a serious accident, where recovery
may be substantially longer. Length of stay in Ward N3 is more likely to be more variable, with some
patients suffering from very serious respiratory conditions remaining on the ward for several weeks.
Ward M4 is a surgical ward where the procedures utilised are of a more standard nature. As such
patients on this ward tend to be discharged more quickly.
0 20 40 60 80 100
< 1 week
1- 2 weeks
2 - 3 weeks
3+ weeks
Percentage (%)
Le
ng
th o
f st
ay
D8 (n=47)
N3 (n=13)
M4 (n=14)
Figure 9.40 Length of patient stay when completing the questionnaire
The presence of a hearing impairment was also explored, with 39% of respondents on Ward D8, 31%
on N3 and 14% on Ward M4 indicating that they did suffer to some degree. The high incidence of
hearing impairment on wards D8 and N3 probably reflects the age profile on these wards. However it
is not clear why the incidence is lower on ward M4 which has a similar age distribution; it may be due
to the fact that the majority of patients on this ward are male and may be more reluctant to admit to a
hearing problem.
The bed number of the respondent was noted on the front of the questionnaire by the ward clerk. This
number provided useful location information which is considered when investigating relationships
between bed positioning and patient accommodation type and noise annoyance and disturbance,
which are explored in Chapter 11. In terms of the single room / multi bed bay split, 99% of
respondents in Ward D8 were staying in multi-bed bays, with 85% in each of the wards N3 and M4.
9.10.2. Noise annoyance and disturbance
The questionnaire sought to identify the sources of noise that may annoy or disturb patients.
Respondents were given two lists of noises and were asked to rate the day time annoyance and night
time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4 indicated a
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great deal). Several lines were left blank at the bottom of the lists for patients to add and rate
additional noise sources.
Patients were first asked how they perceived the day time noise environment on the ward. Figure 9.41
details the responses, which shows over 60% of patients in Ward D8 found the ward ‘a little noisy’,
with similar percentages finding Wards N3 and M4 to be ‘quiet’. Interestingly, when asked whether
they were annoyed by noise, a relatively low percentage (26%) of patients in Ward D8 felt annoyed,
with even lower percentages of 15% and 21% of patients in Wards N3 and M4 respectively.
0 20 40 60 80
Very quiet
Quiet
A little noisy
Very noisy
Extremely noisy
Percentage (%)
Pa
tie
nt
pe
rce
pti
on
of
the
da
yti
me
wa
rd
en
vir
on
me
nt
D8 (n=47)
N3 (n=13)
M4 (n=14)
Figure 9.41 Patient perception of the day time ward noise environment
The patients who had indicated that they were annoyed by noise during the day, were then asked to
rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’
and 4 indicating ‘a great deal’. With relatively small patient samples in wards N3 and M4, the number
of people annoyed by day time noise was too low for any meaningful analysis (n=2 and n=3
respectively). However in ward D8, which had a larger sample, 12 patients rated day time noise as
annoying, and consequently their ratings are worth examining further. Figure 9.42 shows the
percentage of patients within this sample who rated a noise event with a 2, 3 or 4, and as such could
be said to be more than a little annoyed by the event.
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0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
Nurse call
Footsteps
Medical Equipment
People talking
Cleaning
Rubbish bins
Trolleys
Visiting time
Meal times
TV / radio
Mobile phones ringing
Talking on mobile phones
Patients crying out
% of patients who rated each event 2 or above in terms of day time noise annoyance
D8 day time annoyance (n=12)
Figure 9.42 The percentages of patients on Ward D8 rating an annoyance noise event
with a 2, 3 or 4
It can be seen that patients crying out and the internal telephone are the most highly rated noise
events, with nearly 60% of patients in the sample annoyed by each source. Ward D8 has a female
only elderly trauma unit of 13 beds, with any elderly male patients admitted on the ward sharing the
same bay accommodation as the other male patients. Many of the elderly patients suffer from a
degree of confusion or dementia and are likely to cry out, but of course patients who are in a great
deal of discomfort will also vocalise their pain.
There are four internal telephones at the main nurse station in Ward D8, and in some of the other
patient bays there are staff desks with a telephone. If these phones are left unanswered, or take some
time to divert, this could explain this level of annoyance. Visiting time, medical equipment alarms and
people talking are also cited as annoying by over 30% of patients in this ward.
Two patients in Ward D8 added an additional noise event that they themselves found to be annoying
during the day. The events were:
� Staff in a ‘performing mood’
� External building work
Patients were asked how they perceived the night time noise environment on the ward. Figure 9.43
details the responses, which can be seen to be a little more split than for daytime noise annoyance,
with several patients having more extreme perceptions of night time noise.
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When asked whether they were disturbed by noise at night, 51% of patients in Ward D8; 33% of
patients in Ward N3; and 57% of patients in Ward M4 felt they were. Thus overall approximately 50%
of patients were disturbed by noise at night; this figure is similar to that in Bedford Hospital.
0 10 20 30 40 50
Very quiet
Quiet
A little noisy
Very noisy
Extremely noisy
Percentage (%)
Pa
tie
nt
pe
rce
pti
on
of
the
nig
ht
tim
e w
ard
en
vir
on
me
nt
D8 (n=47)
N3 (n=13)
M4 (n=14)
Figure 9.43 Patient perception of the night time ward noise environment
Patients who had indicated that they were disturbed by noise during the night were asked to rate the
annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’ and 4
indicating ‘a great deal’. Sample sets were higher than for the day time annoyance with n=23 for Ward
D8, but were small for wards N3 and M4 (n=5 and n=7 respectively). Again it is possible that in these
cases, only those patients who had felt they had something specific to say about noise may have
chosen to take part in the survey, therefore skewing the results to a degree.
Figure 9.44 shows the percentages of patients within these samples who rated a noise event with a 2,
3 or 4, and so could be said to be more than a little disturbed by the event.
It can be seen that of those patients who were disturbed by night time noise in Ward D8, around 40%
of respondents found that patients crying out, people talking, medical equipment alarms and the
internal telephone were disturbing. This was a very different split to the other wards. In Ward M4 it
was the internal telephone that was rated as disturbing by the most respondents – over 70%. This far
exceeded the ratings for any other sources of disturbance on Ward M4, with doors banging, staff
talking on the telephone and patients crying out, rated by around 30%. Ward N3 again showed
differences, with the nurse call system cited as disturbing by the highest percentage of patients
(60%), and trolleys, people talking, medical equipment and doors banging cited by 40% of
respondents.
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0 10 20 30 40 50 60 70 80 90 100
External noise
Doors banging
Internal telephone
Staff talking on the telephone
Nurse call
Footsteps
Medical Equipment
People talking
Rubbish bins
Trolleys
TV / radio
Mobile phones ringing
Talking on mobile phones
Patients crying out
% of patients rating night time disturbance event of 2 or above
D8 night time annoyance (n=23)
N3 night time annoyance (n=5)
M4 night time annoyance (n=7)
Figure 9.44 The percentages of patients rating a disturbance noise event with a 2, 3 or 4
It can be seen that ‘mobile phones ringing’, ‘talking on mobile phones’ and ‘rubbish bin’ noise are
cited as a disturbance only on Ward D8. It is possible that, with regards to the use of mobile phones
on this ward, the policy may be more lenient than on wards N3 and M4. Also, the rubbish bins in this
ward are possibly older metal bins, rather than bins of a newer, quieter design installed in some of the
more recently built wards.
Four patients added an additional noise event that they themselves found to be disturbing at night.
The events were:
� Snoring (D8)
� Generally noisy bed neighbours (D8)
� Vibration of the floor (N3)
� Nurses talking (N3)
Interestingly, the timber floor construction in Ward N3 does appear to add to the disturbance in some
cases, with a patient specifically citing vibration of the floor, and higher numbers of patients on this
ward disturbed by trolleys (40%) and footsteps (20%) than on Wards D8 and M4.
9.10.3. Positive sounds
Looking at sound in a positive rather than in a negative light, patients were asked if there were any
sounds that they actually found comforting. Most patients left the answer blank (70% in ward D8; 77%
in ward N3; and 86% in M4), however, there were nineteen completed responses which were similar
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in content to those from Bedford Hospital. Responses included listening to music on the radio,
knowing that the nursing staff were nearby to provide care, the tea trolley, droning sounds (such as
the hoover and floor cleaner), and maintaining some connection with the outside world. The full
responses can be seen in Appendix B.
Respondents were also asked if they felt that there was ever too little sound in a room. Only three
patients in total said that they did. Unfortunately, two of these patients did not complete the details
regarding their accommodation, but the other respondent was in a single room.
9.10.4. Ease of hearing and privacy
Patients were asked whether high levels of background noise may at times make it difficult to hear
doctors and nurses who talk to them. 42% of respondents on Ward D8 felt that this was the case, with
this percentage made up of 12 hearing impaired patients and six patients who did not indicate any
hearing problem. On Wards N3 and M4 however, only one respondent from each felt that high levels
of background noise made it difficult to hear, and both these patients were hearing impaired.
Conversational privacy was investigated by asking whether the patient felt that they could have a
private conversation at their bedside. The lowest percentage of patients who felt they could speak
privately was in Ward D8 (59%), which is unsurprising given the bay sizes and bed spacing in this
ward. Out of those who felt they could speak privately, 56% of patients on this ward felt that they
would need to lower their voice. On wards N3 and M4, 69% and 79% of patients respectively felt that
they could speak privately at their bedside. Out of those who felt they could speak privately, 71% on
Ward N3 and 73% on Ward M4 felt that they would have to lower their voice. All respondents in single
patient rooms on these wards (n=4) were happy with conversation privacy.
9.11. Questionnaire comments
Staff and patients were invited to make additional comments at the end of the questionnaire if they
wished. Very few staff made comments, but many patients did leave some feedback which was very
varied. Several patients cited noise from the wearing of high heeled shoes; crying out and shouting of
other patients was disturbing or distressing; and noise attributable to visiting times and the lack of
enforcement of visiting hours by staff was mentioned by several patients; A detailed list of these
comments is shown in Appendix B.
9.12. Summary
This section summarises the main findings from the study of the three wards at Addenbrooke’s
Hospital:
� The nurse station in Ward D8, had the highest average noise levels of all the nurse stations
measured in the three study wards, with day time levels of around 58 dB LAeq and night time
levels of around 53 dB LAeq. Typical sources of noise here included high levels of conversation,
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administrative tasks, furniture scraping on the floor and the closing of desk drawers. The nurse
station in ward N3 had the lowest measured levels, with day time levels of around 53 dB LAeq and
night time levels of around 47 dB LAeq. 48% of high level noise events captured here were due to
the banging of the clean and dirty utility room doors, and so levels could be lowered still further,
with different opening mechanisms installed on these doors. The smaller nurse station in Ward
M4, also suffered from noise due to the banging of the dirty utility room door. Other sources of
high level noise captured at the nurse stations in this ward were primarily due to high levels of
conversation, and corridor traffic.
� Noise level measurements made in the multi-bed bays in Ward D8 were consistently higher both
during the day and night than on the other wards. This ward provided a mixture of patient
accommodation with 3-bed, 4-bed, 7-bed and 12-bed bays. Noise levels were very consistent
throughout , and did not appear to be affected by the number of patients occupying the bays,
with some of the highest levels measured in a 3-bed bay for elderly patients. Many of the high
level noise events identified were related to activity at the nurse’s desk in the 12-bed bay, and
confused elderly patients crying out in the bays in the elderly trauma unit.
� Noise levels measured in the multi-bed bays in Wards N3 and M4 were similar, with day time
levels of around 53 dB LAeq and night time levels of around 44 dB LAeq, with little variation
between the bays. However, subsequent investigation of the numbers of high level noise events
recorded in each bay indicated differences in the noise climate.
� Single rooms were found to have less consistent patterns of noise levels which in some cases
were found to be higher than those measured in multi-bed bays. Staff activity, and patient and
visitor behaviour was shown to be the main reason for this.
� All measured levels in the patient accommodation were above those suggested by the WHO
guidelines and the day / night division specified by the WHO did not appear to be realistic.
� Over 50% of staff in all three wards rated medical equipment alarms and the internal telephone
as annoying noise events, with people talking and staff talking on the telephone rated by 30% of
respondents in each ward. However, opinion on the annoyance of other noise sources was more
split. High percentages of staff on Ward M4 rated both the nurse call and ward doorbell as
annoying; whereas more staff in wards D8 and N3 rated visiting time, the use of mobile phones
and of TV / radio. In the modular ward, Ward N3, higher percentages of respondents rated the
noise from trolleys, footsteps and external noise as annoying than on the other two wards. Noise
of footsteps and trolleys may be magnified on this ward by the construction of the timber floor.
� 62% of patients in Ward D8 found the ward to be ‘a little noisy’ during the day, with patients
crying out, the internal telephone ringing and visiting time cited as the most annoying events,
whereas on wards N3 and M4, over 60% of patients found the wards ‘quiet’ or ‘very quiet’ during
the day.
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� Of those questioned, 51% of patients in Ward D8; 33% of patients in Ward N3; and 57% of
patients in Ward M4 felt that they were disturbed by noise at night. Opinion was split with patients
crying out, people talking, medical equipment alarms and the internal telephone disturbing
patients in Ward D8; the internal telephone far outranking any other source of noise disturbance
in Ward M4; and the nurse call system cited as disturbing by the highest percentage of patients
in Ward N3, followed by medical equipment alarms, people talking and doors banging.
9.13. Conclusions
As in Bedford Hospital, noise level measurements and questionnaire surveys have confirmed that
noise is a problem in both medical and surgical wards. Staff responses indicate that they are annoyed
by noise, and a significant number of patients questioned felt that they were disturbed by noise during
the night, a time when they should be able to rest and recuperate.
Noise levels did not appear to be related to occupancy levels, with similar levels measured in both
four and six bed bays, and higher levels measured in single patient rooms than in the multi-bed bays
on occasions.
Much of the high level noise identified could be reduced with changes to behaviour, correct
enforcement of hospital policies, simple improvements to design and maintenance of equipment. This
is discussed further in Chapter 12.
The following chapter investigates the use of the Maximum Likelihood Estimation method to estimate
reverberation times in occupied wards using the data captured during the study.
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10. Blind estimation of reverberation time
10.1. Introduction
Reverberation time (RT) is generally used as an indicator of the acoustic comfort of a space and is an
important measurement in the field of room acoustics. There are several standard methods used to
calculate the RT of a room, however these rely on generating high level noise, which would be
unacceptable in an occupied hospital ward. All of the wards taking part in the main study were at
capacity at all times and therefore it was not possible to make physical RT measurements in these
wards.
An alternative estimation technique was identified that could possibly be used with some of the noise
measurement data collected in the study wards. The method was developed at Salford University
(Kendrick, Cox and Li, 2007; Kendrick et al, 2011) and is known as the Maximum Likelihood
Estimation (MLE) method. The technique had been successfully used to estimate a number of
acoustic parameters ‘blind’ (including RT), by using sounds already present in a room such as speech
or music.
As discussed in previous chapters, the noise measurement data collected from the wards contained
numerous discrete sound files or ‘trigger files’, created when LAmax exceeded 70 dB. These files were
between six and ten seconds in length and contained sounds such as speech; impulsive noises, for
example, rubbish bins, doors banging and dropped objects; bed rails; and other sounds associated
with general movement in a space. It was thought that these trigger files may be suitable for use with
the MLE algorithms, and therefore could potentially be of use in estimating the RT20 (MLE-RT20) of the
occupied wards. However, extensive validation would be required to prove that accurate estimates
could be obtained.
This chapter begins by describing the validation of the MLE-RT20 method using measurement data
from the surveys of Bedford and Addenbrooke’s Hospital and from a simulated hospital environment.
Following the discussion of the validation, the maximum likelihood method is used to estimate
reverberation times for a number of occupied study wards.
10.2. Initial validation
The MLE-RT method works by identifying short periods of reverberant decay within a noise dataset
where the dynamic range is greater than 25 dB. Data selection techniques are used to ensure correct
recognition of suitable decay phases, and the mean RT is estimated from multiple values. To ensure
estimates are accurate, the method relies on a large amount of suitable data. More details of the
method are provided by Kendrick (2009; 2011).
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As the MLE-RT method was initially developed for use with speech or music, it was unknown whether
it would work with the trigger files collected. It was thought that if the files were of a reasonable sound
quality, and enough suitable decays could be identified, then the discrete nature of the files would not
necessarily prevent the method from working. Consequently, trigger files collected during noise
measurements in a 4-bed bay during the pilot study were sent for initial processing.
The sound level meter (SLM) had a number of settings which could be adjusted to change the format
and quality of the audio file recordings. These settings included three different word lengths of 8, 16
and 24-bit; two sampling frequencies at 12 kHz and 48 kHz; and the recording gain. The word length
and sampling frequencies affect the size of the file, and so with limited storage available on the meter,
these had been initially set to minimum values for the pilot study. The gain setting increases the
loudness of the recorded sound file, and had been set fairly high, to ensure playback on a laptop
would be easily audible during analysis.
Following the initial processing of the trigger files, a number of issues with the data were found. The
low quality of the audio recording caused a number of dropouts, and the high gain setting caused a
certain amount of clipping. Both these issues needed to be resolved before the data would work with
the MLE algorithms. It was felt however, that the type of sounds recorded would be suitable, and if the
audio issues were resolved, the data would probably be capable of yielding some reasonable results.
The audio quality settings were subsequently changed to 24-bit sampling at a frequency of 12 kHz
with a gain of 24 dB. These were considered to be the optimal settings in terms of both audio quality
and file size, and would allow estimations up to 4 kHz to be computed. With confidence in the discrete
data files established, the next step was to perform a simulation experiment to compare the accuracy
of estimated MLE-RT values with RTs measured in a laboratory space. This is discussed in the next
section.
10.3. Validation using real and simulated measurements
To test the accuracy of the estimated RT values against those measured, a scenario was developed
that would allow both real time RT measurements to be made along with the recording of noise data
consisting of the type of sounds that would be found in an occupied hospital ward.
A new building had recently opened at London South Bank University, which was used in part for
nurse training. Several clinical skills laboratories were laid out as hospital wards to provide students
with clinical practice space. Each laboratory was equipped with standard hospital furniture including
beds with rails, bed tables, dustbins, sinks, privacy curtains and wheeled equipment. It was thought
that within this environment it would be easy to create a noise climate similar to that of an occupied
ward. This would allow enough trigger files to be captured to provide data for the MLE-RT method.
Real time RT measurements could also be made using an impulsive noise source and the results
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compared to the estimates generated. Two validation experiments were carried out and are discussed
in the following sections.
10.3.1. Validation 1
The clinical skills laboratory used for the first validation, shown in Figure 10.1, had a volume of 171
m3. The ceiling was exposed concrete soffit; the floor was concrete with a heavy duty vinyl covering;
and the walls were plasterboard. As can be seen from Figure 10.1, the room was fully furnished, and
included dummy patients in the beds.
Figure 10.1 Clinical skills laboratory used for validation 1
RT measurements were made using thick latex balloons as an impulsive noise source. Six
measurements were made; with three source and two receiver positions. Figure 10.2 shows the
spatially averaged RT20 values over third octave bands from 250 Hz to 4 kHz as stipulated in BS EN
ISO 3382-2 (2008). At 500 Hz and above the 95% confidence limits for each RT20 value are within
±0.1 s, suggesting good accuracy at these frequencies. However, accuracy at 250 to 400 Hz is lower,
with slightly more measurement variation at these frequencies.
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k
RT
20 (
s)
Frequency (Hz)
Figure 10.2 Average RT20 measurements with 95% confidence limits (Impulse Response Method)
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A 60 minute noise measurement was made within the room during which noise was created that
would be comparable to that found in an occupied hospital ward. Noise included conversation; moving
of furniture and bed rails; use of rubbish bins and sinks; dropping objects; and opening and closing of
doors. During this measurement period 149 trigger files (sound files where LAfmax exceeded 70 dB)
were created, totalling approximately 20 minutes in length. This data was sent to the University of
Salford for processing.
Table 10.1 shows both the measured and estimated RT values and the difference between them. Due
to the processor intensive nature of the algorithm used in the MLE-RT method, only octave band RT
values are estimated.
Table 10.1 Comparisons between measured and MLE-RT20 values
Frequency
(Hz)
Measured
T20 (s) MLE-RT20 (s)
Difference
(s)
250 0.712 0.710 -0.002
500 0.712 0.828 0.116
1000 0.706 0.771 0.065
2000 0.722 0.702 -0.020
4000 0.707 0.709 0.002
It can be seen that the results show reasonable accuracy with less than 0.1 s difference in the
majority of cases (differences greater than 0.1 s are highlighted in green). The value 0.1 s is of
particular significance when estimating RT values because of the subjective difference limens.
Kendrick (2009; 2011) discusses that in order to judge the performance of a measurement method it
must be compared against the ability of the human ear to detect subtle changes in acoustic
conditions. Subjective difference limens are the smallest change in a parameter value that can be
detected and are determined using ‘just noticeable differences’. Bork (2000) shows that in a room with
an RT value of 2 s or less, the subjective difference limen is 0.1 s, and hence any change in the RT
that is less than 0.1 s would be inaudible to the listener.
10.3.2. Validation 2
Following the positive results obtained during the first validation, it was felt that further simulations in
different acoustic conditions would be required to reinforce the initial outcome. Another clinical
laboratory of different dimensions (153 m3) was available for use and it was decided to perform
several sets of tests within this room. Apart from the room volume, the layout and finishes were
identical to those of the first room used.
To ensure as much data as possible was collected, the acoustic room conditions were varied. This
was achieved by fully drawing the privacy curtains around the beds during one test scenario and then
opening all the curtains for a second scenario. Two identical Norsonic 140 sound level meters (SLM1
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and SLM2) were used to make noise level measurements of the simulated hospital sounds. The
meters were situated on different sides of the room and hence captured slightly different levels, thus
providing further data for validation purposes.
Two sets of real time RT measurements were made using the same impulse response method as in
the previous validation; one set with the privacy curtains open; the other with the curtains drawn. As
before, six measurements were made in each case; with three source and two receiver positions. The
measured results were found to be consistent above 500 Hz, with 95% confidence limits for each
mean RT20 value within ± 0.1 s, but with some inconsistencies found at 500 Hz and below, as shown
by Figure 10.3. It can be seen that as a result of drawing the curtains, RT20 values were reduced by
between 0.1 s and 0.3 s.
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k
RT2
0 (
s)
Frequency (Hz)
Curtians drawn
Curtains open
Figure 10.3 Average RT20 measurements with 95% confidence limits (Impulse Response Method)
Two 60 minute noise measurements were made within the room on each SLM, with curtains open
and curtains drawn. Again noise was created that would be comparable to that found in an occupied
hospital ward. Table 10.2 shows the number of trigger files recorded during each scenario by each
SLM.
Table 10.2 Numbers of triggers recorded during the simulations
Number of trigger files recorded
Curtains open
Curtains drawn
SLM 1 188 164
SLM 2 233 196
The trigger files recorded were used to provide MLE-RT20 estimates for the four scenarios. The
estimates were compared with the actual measured values and the results can be seen in Tables
10.3 to 10.6. Differences greater than 0.1 s are highlighted in green.
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Table 10.3 SLM 1 with curtains open Table 10.4 SLM 1 with curtains drawn
Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s) Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s)
250 0.775 0.752 -0.023 250 0.684 0.660 -0.024
500 0.812 0.949 0.137 500 0.704 0.628 -0.076
1000 0.861 1.004 0.143 1000 0.645 0.640 -0.005
2000 0.910 0.904 -0.006 2000 0.646 0.734 0.088
4000 0.921 0.963 0.042 4000 0.659 0.619 -0.040
SLM 1 - Curtains Open SLM 1 - Curtains Drawn
Table 10.5 SLM 2 with curtains open Table 10.6 SLM 2 with curtains drawn
Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s) Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s)
250 0.775 0.794 0.019 250 0.684 0.652 -0.032
500 0.812 0.928 0.116 500 0.704 0.778 0.074
1000 0.861 0.940 0.079 1000 0.645 0.672 0.027
2000 0.910 1.067 0.156 2000 0.646 0.666 0.020
4000 0.921 1.014 0.093 4000 0.659 0.692 0.033
SLM 2 - Curtains Open SLM 2 - Curtains Drawn
The results show good accuracy with the curtains drawn, but slightly less so with the curtains open,
with two octave frequency bands showing a difference slightly above 0.1 s in each case, which is just
outside the difference limen for RT. It is thought that this is primarily due to the number of suitable
decay phases with a sufficient signal to noise ratio available for analysis at these frequencies.
Figure 10.4 further illustrates the accuracy of the MLE-RT20 estimates, by plotting the estimated
values against the measured values. The 0.1 s difference limens are represented by dashed lines.
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
MLE
-RT
20
(s)
Measured T20 (s)
SLM1 - Curtains open SLM1 - Curtains closed SLM 2 - Curtains open SLM2 - Curtains closed
Figure 10.4 Accuracy of RT20 estimations in relation to actual measured values
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10.3.3. Validation study conclusions
The validation study demonstrated that with the change of audio settings, the trigger file data could be
successfully analysed using the MLE-RT20 method. The accuracy of the estimates was reasonable
overall, but some small inconsistencies were found for the different room conditions. This was
primarily due to insufficient data with suitable regions of decay. Given that the data captured in the
simulation was captured for a relatively short time period (60 minutes) and that measurements made
during the main study were over a seven day period, it was considered likely that sufficient data would
be available to provide reliable estimates of reverberation times in occupied hospital wards.
10.4. Estimation of RT in occupied hospital wards
The validation study described in the previous section yielded on average 1.4 samples of data with
suitable free reverberant decay per minute. Examination of the trigger files from the occupied wards
showed the density of suitable data was approximately eight times less than in the validation study.
Previous testing of the MLE-RT20 method had established a minimum amount of suitable data needed
to produce accurate estimates, and when this was applied to the hospital data it was calculated that at
least forty hours of measurement data would be required to provide enough suitable decays. As
discussed previously, the measurement data collected from the occupied hospital wards was over a
period of approximately seven days, and as such should provide ample data to produce an accurate
estimate of RT. Table 10.7 shows the data available for use with the MLE-RT20 method, which
consisted of data from 17 different spaces. Data was not available from all wards due to poor quality
audio files.
Table 10.7 Locations with data available for MLE-RT20 estimation
Hospital Ward Areas for which MLE-RT data is
available
Addenbrookes D8 2 x 3-bed bays, 1 x 4-bed bay, 1 x 7-bed bay,
1 x 12-bed bay
Addenbrookes N3 3 x 4-bed bays, 2 x single rooms
Bedford Surgical 2 x 4-bed bays, 1 x 6-bed bay, 2 x single rooms, nurse station
Bedford Medical Pre and post ceiling tile change in 4-bed bay
10.4.1. Methodology
For each room, the trigger files captured over the entire measurement period (generally seven days),
were segmented into two groups: from 06.00 to 18.00 (day); and from 18.00 to 06.00 (night). The day
and night split chosen was not the same as was used in rest of the study, as too little data would exist
for the period 23.00 to 07.00 for estimation purposes. Data was grouped in this way for two reasons:
(i) to reduce the possibility of compromising day time estimates with potentially less accurate night
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time estimates (due to the lower amount of suitable data available at night); (ii) to allow comparisons
to be made between day and night time estimates (given that night time data was found to be
sufficiently accurate). This comparison could yield interesting information regarding the effects of ward
conditions on the MLE-RT20 estimates, mostly in relation to occupancy levels (no visitors and less
clinical and domestic activity at night and hence less acoustic absorbency).
Estimates were computed for octave frequency bands 250 to 4000 Hz, for the two groups of data.
Lower frequencies were discarded, as previous experience of this method with other data sets
showed inaccuracies at frequencies less than 250 Hz.
For each data group, initial estimates were calculated from suitable decays captured during four hour
windows of data. An example of this can be seen in Table 10.8 for the day time data. The final MLE-
RT20 estimate for each day and night group was computed by calculating the mean of all the
estimates over the measurement interval.
Table 10.8 Day time data shown in 4 hour windows; overall mean estimate
with 95% confidence intervals
Mean RT 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00
250 0.500 0.520 0.637 0.332 0.365 0.483 0.445 0.591 0.585 0.539 0.057
500 0.514 0.720 0.500 0.483 0.526 0.461 0.406 0.509 0.568 0.559 0.047
1000 0.541 0.604 0.611 0.494 0.512 0.596 0.455 0.663 0.614 0.579 0.034
2000 0.434 0.693 0.486 0.571 0.652 0.621 0.590 0.649 0.697 0.632 0.041
4000 0.436 0.530 0.416 0.605 0.451 0.510 0.586 0.573 0.621 0.554 0.037
95% CL
(7 days)
Frequency
(Hz)
Day 1 06.00 - 18.00 Day 2 06.00 - 18.00 Day 3 06.00 - 18.00
It has been shown (Kendrick 2009), that by calculating the standard error of these estimates, and by
only accepting measurements where the 95% confidence limits are within ±0.1 s, very good accuracy
is obtained.
10.4.2. MLE-RT20 estimates from day time data
This section graphically presents MLE-RT20 estimates from three different study wards; examines the
accuracy of the estimates; and discusses the effects of the different levels of acoustic absorbency on
the wards.
Figure 10.5 shows the MLE-RT20 day time estimates for five multi-bed bays on Ward D8 at
Addenbrooke’s Hospital. It can be seen that the estimates are between 0.4 s and 0.57 s at 1 kHz. The
majority of estimates have low 95% confidence intervals of around ±0.05s, suggesting that the
estimated RTs are accurate. All 95% confidence intervals calculated for the estimates are within the
±0.1 s difference limen.
This particular ward has little in the way of acoustic absorbency at ceiling level. As explained in
Chapter 9, most ceilings in this ward consist of metal pan tiles which work in conjunction with the
heating system, by radiating heat from the hot water pipes running above them. These tiles are
perforated, and have a layer of insulation covering the water pipes which may provide a level of
acoustic absorbency at some frequencies. The 4-bed bay which is situated behind the nurse station
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has a suspended ceiling grid with solid plaster tiles. It can be seen that it is the larger volume multi-
bed bays with more occupants and hence more absorption, which have the lowest MLE-RT20
estimates, as would be expected.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Est
ima
ted
MLE
-RT
20
(s)
Octave band (Hz)
3-Bed Bay A
3-Bed Bay B
4-Bed Bay
7-Bed Bay
12-Bed Bay
250 500 1000 2000 4000
Figure 10.5 MLE-RT20 estimates for five multi-bed bays in Ward D8, Addenbrooke’s Hospital
(day time data) with 95% confidence limits
Figure 10.6 shows MLE-RT20 estimates for six locations in Ward N3 at Addenbrooke’s Hospital. It can
be clearly seen, that the estimates for 4-bed bay B and single room J are higher than for the other
locations and also have larger confidence intervals, particularly at 250 Hz, where they are greater
than ±0.1 s. As this data falls outside the stipulated ±0.1 s confidence limits, it must be assumed to
be inaccurate and therefore should be ignored. However, the majority of estimates have low 95%
confidence intervals with a mean of ±0.04s, which suggests that the estimated values are accurate.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Est
ima
ted
MLE
-RT
20
(s)
Octave band (Hz)
4-Bed Bay A
4-Bed Bay B
4-Bed Bay C
Single Room J
Single Room K
250 500 1000 2000 4000
Figure 10.6 MLE-RT20 estimates for six locations in Ward N3, Addenbrookes Hospital (day time
data) with 95% confidence limits
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The MLE-RT20 estimates at 1 kHz show much lower RTs than in Ward D8, with all estimated values of
around 0.25 to 0.3 s. All these areas have suspended ceilings with good quality acoustic ceiling tiles.
Figure 10.7 shows MLE-RT20 estimates for seven locations in the surgical ward at Bedford Hospital.
The estimate for 4-bed bay 1 shows confidence intervals which are greater than ±0.1 s at 250 Hz and
therefore this data should be ignored. However, this is the only estimate for the ward where the ±0.1 s
confidence limits were exceeded, with most confidence limits generally low, with values less than
±0.04 s.
The MLE-RT20 estimates at 1 kHz for the nurse station and 4-bed bay 1 show the lowest estimated
values of around 0.25 to 0.3 s. These areas both have a suspended ceiling with acoustic ceiling tiles
and it can be seen that the values are similar to those in Ward N3 at Addenbrooke’s Hospital (see
Figure 10.6), which also had acoustic ceiling tiles. The single rooms and 6-bed bay 3 are similar with
a low value of around 0.35 s. These rooms have either solid plaster ceilings (6-bed bay 3 and single
room 1) or a non acoustic suspended ceiling (single room 3). 4-bed bay 4 has noticeably higher
estimates at all frequencies, with an MLE-RT20 estimate of 0.55 s at 1 kHz. This bay has been
refurbished more recently and has reflective, plaster ceiling tiles throughout.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Est
ima
ted
MLE
-RT
20
(s)
Octave band (Hz)
4-Bed Bay 1
4-Bed Bay 4
6-Bed Bay 3
Single Room 1
Single Room 3
Nurse Station
250 500 1000 2000 4000
Figure 10.7 MLE-RT20 estimates for seven locations in the surgical ward, Bedford Hospital (day
time data) with 95% confidence limits
It appears that the results are consistent with the amount of absorbency provided by the ceiling, with
longer RTs estimated in those rooms with solid plaster ceilings or those with reflective ceiling tiles.
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10.5. Comparison of day and night time MLE-RT20 estimates
As discussed in Section 10.4.1, the data was segmented into day and night groups to allow for
comparisons to be made between times when acoustic conditions on the ward could potentially be
quite different. Day times are busy with visitors; there is a great deal of clinical and domestic activity;
and privacy curtains are often drawn around beds. All these events provide additional absorbency
which could affect the estimated MLE-RT20 values. Night time is a relatively quiet time, with minimal
disturbance by clinical staff, much less ward activity and hence lower additional absorbency. It could
therefore be assumed that the MLE-RT20 estimates would be longer at night than those during the
day, but further analysis of the results is required to establish this.
As expected, due to lower amounts of suitable data, the estimates calculated from the night time data
were much more variable. Many of the 95% confidence limits were found to be in excess of 0.1 s,
therefore the estimates were unusable and no comparisons could be made. However, there were
three instances where enough night time data with suitable decay phases existed. Figures 10.8, 10.9
and 10.10 show the comparisons between the day and night MLE-RT20 estimates in three different
patient bays in Addenbrooke’s and Bedford Hospitals.
.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Est
ima
ted
MLE
-RT
20
(s)
Octave Band (Hz)
Day time estimate 7-Bed Bay
Night time estimate 7-Bed Bay
250 500 1000 2000 4000
Figure 10.8 Comparison of day and night time estimates, 7-bed bay, Ward D8,
Addenbrooke’s Hospital
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Est
ima
ted
MLE
-RT
20
(s)
Octave Band (Hz)
Day time estimate 12-Bed Bay
Night time estimate 12-Bed Bay
250 500 1000 2000 4000
Figure 10.9 Comparison of day and night time estimates, 12-bed bay, Ward D8,
Addenbrooke’s Hospital
0
0.1
0.2
0.3
0.4
0.5
0.6
250 500 1000 2000 4000
Est
ima
ted
MLE
-RT
20
(s)
Octave Band (Hz)
Day time estimate 4-bed bay
Night time estimate 4-bed bay
Figure 10.10 Comparison of day and night time estimates, 4-bed bay,
medical ward, Bedford Hospital
It can be seen from each figure, that the night time estimates are slightly higher than the day time, as
would be expected. However, the differences between the day and night time estimates for the seven
and 12-bed bays are very small, as little as 0.01 s at some frequencies. In the four bed bay, where
more data was available (12 days rather than seven), the MLE-RT20 estimate can be seen to be at
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least 0.05 s lower during the day in each octave band (with slightly larger differences found at lower
frequencies).
During a 24 hour period the acoustic conditions on a hospital ward are constantly changing due to
occupancy levels, opening and closing of privacy curtains, opening windows and many other aspects.
There is no easy way to record all of the conditions in the ward at a given time. It can therefore be
said that MLE-RT20 estimates are representative of snapshots of the acoustic conditions on the ward
when they are at their least reverberant. To explain this further, the MLE-RT20 method works by
searching the dataset for the fastest decaying region over a given four hour time window and hence
each estimate will be consistent with the highest occupancy / highest absorption on the ward.
Where night time estimates were available for comparison, they were found not to differ greatly from
the day time estimates, which indicates that the acoustic conditions on the wards were fairly stable at
all times.
10.6. Summary
The application of the MLE-RT20 method was investigated for use with discrete sound or trigger files
collected in occupied hospital wards. After rectifying initial audio quality issues, a number of validation
studies were carried out in simulated hospital wards. In each study, high trigger files (generated when
LAMAX exceeded 70 dB) were collected over a 60 minute period and a reverberation time estimate
(MLE-RT20) was calculated and compared with actual RT20 measurements made in the rooms using
an Impulse Response Method. Initial findings from the validation studies were positive, but highlighted
the need for sufficient data with uninterrupted reverberant decays, meaning significantly longer
recordings would be required.
The MLE-RT20 method was applied to data from noise measurements made in a number of ward
locations, at Bedford and Addenbrooke’s Hospitals. Each measurement interval was at least seven
days in length and the trigger files captured were segmented into day and night time groups. For each
data group, a day and night mean estimate was calculated for the entire measurement period.
For the day time MLE-RT20 estimations, in the octave bands 500 to 4000 Hz, the worst case 95%
confidence limits indicated a maximum error of ±0.08 s and as such the MLE-RT20 estimation method
can be said to demonstrate similar accuracy to standard measurement methods such as the Impulse
Response Method.
Night time MLE-RT20 estimations were found to be less accurate due to the availability of suitable
data, but it is felt that this could be further improved by longer measurement periods. Comparisons of
the night and day estimates provide an indication of the variation of acoustic conditions on the wards,
and were found not to differ greatly. This suggests that the acoustic conditions on the wards were
fairly stable at all times despite increased activity and occupancy levels.
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10.7. Conclusions
An estimation method which provides information regarding reverberation times in occupied spaces
has been trialled and has been shown to demonstrate similar accuracy to standard measurement
methods such as the Impulse Response Method.
The data provided by this method can usually only be generated using complex and time consuming
modelling techniques, and as such the MLE-RT20 method could be used to provide reverberation time
estimates in occupied areas where real time measurements are not practical or possible.
The following chapter presents some overall results from the main study; looking for general trends
and relationships within the objective and subjective data collected.
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11. Analysis of objective and subjective data
11.1. Introduction
Analysis of the noise level data and questionnaire responses for each of the main study wards has
been carried out and presented in Chapters 7 and 9. This chapter aims to explore the overall results;
looking for general trends and relationships within the objective and subjective data collected from the
main study. Due to the differences in the care group, results from the pilot study are not considered in
this chapter.
The chapter begins by summarising the objective and subjective data collected in the study, as shown
in Table 11.1, which lists factors such as building age; ceiling types; ward configuration; measurement
durations and numbers of questionnaire responses.
The chapter continues by examining the objective data to investigate factors which might affect the
acoustic environment of a hospital ward. The physical aspects of the room design are considered and
relationships between noise levels and factors such as bay size are explored.
Patient perceptions are studied, with the effects of gender, age, hearing, length of stay and bed
position on noise annoyance and disturbance investigated. Aspects of privacy and speech
intelligibility are also examined.
The final part of this chapter considers staff perceptions of noise annoyance and interference with
work, and examines factors such as gender, age, and length of service.
11.2. Factors affecting noise levels
11.2.1. Effect of bay size
There is a general assumption among the acoustic, medical and architectural professions that the
larger the size of bay (that is the higher the number of patients in a bay), the greater the potential
noise level. In their 2004 paper on the role of the physical environment in the hospital of the 21st
Century, Ulrich et al (2004) state that ’a clear-cut finding in the literature is that noise levels are much
lower in single-bed than multi-bed rooms’. The data was therefore examined to see if this was found
to be the case in the current study.
Figure 11.1 shows the day time noise levels (LAeq,16hr) for each bay size, with the different study wards
represented by different bar colours. Interestingly, many of the noise levels measured in the single
rooms and three bed bays can be seen to be as high as those measured in the seven and twelve bed
bays. In fact the highest measured day time level is 60.6 dB LAeq,16hr which was measured in a single
room.
Table 11.1 Summary of the objective and subjective data collected during the study
Details
Hospital GOSH Addenbrooke's Addenbrooke's Addenbrooke's Bedford Bedford
Building Type PFI PFI 1970's tower Modular build Early 1980's build Early 1980's build
Age < 10 years < 10 years 50 years < 10 years 30 years 30 years
Ward Name Sky M4 D8 N3 Elizabeth Howard
Ward Type Surgical Surgical Trauma / Orthopaedics Respiratory care Medical Surgical
Ward capacity 18 32 35 25 30 26
Ward Config 2 x nurse stations;
3 x 4-bed bays;
6 x single rooms
2 x nurse stations;
5 x 4-bed bays;
12 x single rooms
1 x nurse station;
1 x 12-bed bays;
1 x 7-bed bay;
1 x 4-bed bay;
3 x 3-bed bays;
3 x single rooms
1 x nurse stations;
4 x 4-bed bays;
9 x single rooms
1 x nurse station;
3 x 6-bed bays;
2 x 4-bed bays;
4 x single rooms
1 x nurse station;
1 x 6 bed bays;
4 x 4 bed bays;
4 x single rooms
Ceiling tile type Acoustic in patient acc /
plaster in common areas
Acoustic throughout Metal pan with some
insulation
Acoustic throughout Acoustic throughout Acoustic throughout
Measurement: Location and length
Multi-bed bays 4 bed bay A - 10 days;
4 bed bay B - 5 days;
4 bed bay A - 6 days;
4 bed bay B - 8 days
3 bed bay A - 7 days;
3 bed bay B - 7 days;
4 bed bay - 8 days;
7 bed bay - 6 days;
12 bed bay - 2 non
consecutive 7 day
periods
4-bed bay A - 7 days;
4-bed bay B - 8 days;
4-bed bay C - 7 days
4-bed bay 1
(refurbished) -12 days
(over 2 non consecutive
weeks);
4-bed bay 2 - 7 days;
6-bed bay 3 - 6 days;
6-bed bay 4 - 8 days
4-bed bay 1 - 6 days;
6-bed bay 3 - 8 days;
4-bed bay 4 - 7 days
Single rooms Single room A - 5 days;
Single room B - 5 days
Single room A - 7 days;
Single room B - 9 days
Single room J - 7 days;
Single room K - 9 days
Single room A
(refurbished) - 5.5 days;
Single room B - 7 days
Single room A
(refurbished) - 7 days;
Single room B - 7 days
Nurse Stations Nurse station 1 - 10 days;
Nurse station 2 - 5 days
Nurse station 1 5 days;
Nurse station 2 - 7 days
Nurse station - 6 days Nurse station - 5 days Nurse station - 7 days;
Ward clerk's desk area -
7 days
Nurse station - 7 days
Questionnaires: Numbers of responses
Staff Quest reponse 12 10 20 11 18 7
Patient Quest response 31 14 47 13 40 42
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0
10
20
30
40
50
60
70
1 3 4 6 7 12
LAe
q,1
6h
r (d
B)
Bay size (number of patients)
■ Ward M4, Addenbrookes, ■ Ward N3, Addenbrookes, ■ Ward D8, Addenbrookes
■ Medical ward, Bedford, ■ Surgical ward, Bedford
Figure 11.1 Average day time levels by bay size for all main study wards
The relationship between the average day time noise level for each bay and bay size was
investigated, but this was not statistically significant (ρ=.038, ns).
Figure 11.2 shows average night time noise levels (LAeq,8hr) in each bay, grouped according to bay
size with the different study wards represented by different bar colours. It can be seen that some of
the highest average night time noise levels were measured in single rooms and three bed bays.
0
10
20
30
40
50
60
1 3 4 6 7 12
LAe
q,8
hr
(dB
)
Bay size (number of patients)
■ Ward M4, Addenbrookes, ■ Ward N3, Addenbrookes, ■ Ward D8, Addenbrookes
■ Medical ward, Bedford, ■ Surgical ward, Bedford
Figure 11.2 Average night time levels by bay size for all main study wards
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As with day time noise levels, the relationship between average night time noise levels for each bay
and bay size was not statistically significant (ρ= .014, ns).
11.2.2. Surgical and medical wards
The study has enabled the effect of ward type on noise levels to be examined.
At Bedford Hospital, two inpatient wards of similar layout were chosen in the main five storey ward
block. Both wards were subject to the same general hospital routines and regulations, but one ward
was a surgical ward, the other medical. This provided an opportunity for a comparison to be drawn
between the type of care provided and any differences this may have on the noise environment and
on patient and staff perceptions. More detailed discussion can be found in Chapter 7.
Overall noise levels at the nurse stations were found to be very similar between the wards, but the
content of the noise varied, with more frequent use of the nurse call and higher levels of staff
conversation captured at the surgical ward nurse station. Overall noise levels in the patient
accommodation were also found to be very similar between the wards, except for the bay directly
opposite the main nurse station in the medical ward, where instances of patients crying out and
increased clinical activities increased noise levels. This was specifically related to the numbers of
acutely ill elderly patients in this bay, many of whom were suffering from confusion or dementia.
Surgical and medical wards are very different in the type of services they provide. Surgical wards are
very busy with constant admissions for day or even half day procedures. Operations are booked in
advance and efficiency and timing are imperative. Medical wards are slower paced, with fewer
admissions and longer patient stays. These differences may in part explain the differences in
perceptions which are discussed in the following paragraphs.
Response to the questionnaire survey by staff in the surgical ward was poor, with only seven
completed questionnaires. It is possible that only those staff who felt strongly about noise made the
time to express their opinion. If this is the case, the results may be not wholly representative.
However, it is still worth comparing the staff perceptions between the wards.
Surgical ward staff rated visiting time, internal telephone, meal times, the nurse call, and trolleys as
interfering with their job much more highly than the staff on the medical ward. As this ward is more
fast paced, staff may find the presence of visitors, the constant ringing of the ward telephones and the
serving of meals impacts their efficiency further and hence causes more interference. The increased
use of the nurse call is reinforced by the results of the objective survey, but it is unknown why this is
used more on this ward. Trolleys are known to be used more extensively in the surgical ward with
patients constantly being wheeled through the ward to go to and from surgery and X-ray.
The major difference between patient perceptions was found to be the disturbance caused by patients
crying out at night in the medical ward. This was mainly due to the numbers of elderly patients on the
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ward, many of whom were suffering from confusion or dementia. As with the staff, patients also rated
trolleys and the nurse call more highly on the surgical ward. Other differences in perceptions were
due to maintenance issues on the ward or the lack of enforcement of hospital policy, but as such were
not an indication of the impact of the differences of care provided on the noise environment.
The three study wards at Addenbrooke’s Hospital were also a combination of surgical and medical
wards. However, these wards were not considered suitable for comparison due to the mixture of
different building design variables and care groups.
11.2.3. Impact of high level noise events on overall noise levels
Throughout this study, average day and night noise levels have been calculated for each bay, with
average hourly noise levels plotted over 24 hour intervals. Levels presented in these ways do provide
a general indication of the daily patterns of noise and overall levels measured in each bay, but fail to
illustrate the continuously fluctuating nature of the noise or provide any understanding of its content.
To help build up a more detailed picture of the noise climate, high level noise events (over 70 dB
LAmax) have been investigated and are reported in Chapters 7 and 9. This section examines the
impact of the numbers of high level noise events on the overall noise levels.
Figure 11.3 shows the average day time noise levels for each bay measured plotted against the
average number of day time high level noise events. It can be seen that the data points are a good fit
to the trend line suggesting a strong relationship between the average day time noise levels and
average numbers of high level noise events, confirmed by the statistically significant correlation
coefficient of ρ=.924 (p<0.01).
The gradient of the trend line shows that for every 100 high level noise events occurring during the
day time, there is an increase in the average LAeq,16hr of 1 dB.
y = 0.0101x + 49.88
0
10
20
30
40
50
60
70
0 200 400 600 800 1000 1200
LAe
q,1
6h
r (d
B)
Average number of high level noise events per day
Figure 11.3 Average day time noise levels and average number of day time high level
noise events for each bay
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Night time noise levels and high level noise events have been also examined to see if a similar
relationship exists. Figure 11.4 shows the average night time noise levels for each bay plotted against
the average number of night time high level noise events.
y = 0.0555x + 43.764
0
10
20
30
40
50
60
0 50 100 150 200 250
LAe
q,8
hr
(dB
)
Average number of high level noise events per night
Figure 11.4 Average night time noise levels and average number of night time
high level noise events for each bay
Although there is again a statistically significant relationship (ρ=.737, p<0.01) between noise levels
and the numbers of high level noise events, it is weaker for the night time than for the day time noise.
However, the gradient of the trend line is steeper than for the day time data and shows that for every
21 high level noise events occurring during the night time, there is an increase in the average LAeq,8hr
of 1 dB. This indicates that the effect of high level noise events on the overall noise levels (LAeq,8hr) is
greater at night than during the day and may suggest that these high level noise events cause greater
disturbance during the night. This is confirmed by the subjective responses of patients, where 52%
were disturbed by noise at night in contrast to 21% during the day (see Section 11.3.1).
11.2.4. Noise levels and reverberation times
As discussed in Chapter 10, reverberation times (RT) were estimated using the maximum likelihood
estimation method (MLE-RT20) for those bays with suitable data available. The relationship between
the daytime LAeq, 16hr and day time MLE-RT20 estimates has been investigated and is shown in Figure
11.5. There is a statistically significant correlation between the LAeq, 16hr and the RT, (ρ=.521, p<0.05),
with lower noise levels related to lower reverberation times as would be expected.
The gradient of the trend line shown in Figure 11.5 provides a relationship between the average day
time LAeq,16hr and RT, showing that for every 0.1 s decrease in the RT, there is a decrease in the
average day time noise level of 1.2 dB LAeq,16hr. This relationship is close to that found in the ceiling
intervention study discussed in Chapter 8, where the addition of an acoustically absorbent ceiling was
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found to decrease both RTs and overall noise levels. In this case, a 0.1 s decrease in RT
corresponded to a 1.8 dB reduction in noise level.
y = 12.471x + 50.15
0
10
20
30
40
50
60
70
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
LA
eq
,16
hr
(dB
)
MLE-RT20(secs)
Figure 11.5 Average day time noise levels and estimated reverberation times in each bay
11.3. Factors affecting patient perceptions of noise
Sources of noise annoyance and disturbance to patients were examined in detail in Chapters 7 and 9
in relation to each study ward. These sources were found to be ward specific and it would be
inappropriate to look for general trends in this data. This section aims to look at more general
relationships including whether gender, age, length of stay or bed position exacerbate feelings of
noise annoyance. Privacy, speech intelligibility and the effects of hearing impairment are also
examined.
11.3.1. Overall
Figure 11.6 shows the perception of day and night time noise for all 154 respondents. It can be seen
that the majority of respondents perceive the wards to be either quiet or a little noisy, both during the
day and at night. The more intense perceptions of ‘very noisy’ or ‘extremely’ noisy are chosen by very
few respondents.
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0
10
20
30
40
50
60
70
80
Very quiet Quiet A little noisy Noisy Extremely noisy
Nu
mb
er
of
resp
on
de
nts
Patient percepption of the noise climate
Day time perception
Night time perception
Figure 11.6 Overall patient perception of the noise climate
Figure 11.7 shows the percentages of all 154 respondents who indicated that they were annoyed by
day time noise and disturbed by noise at night. A relatively low percentage (21%) of patients felt
annoyed by noise during the day, but over half those patients questioned (52%) were disturbed by
noise at night.
0
10
20
30
40
50
60
Pe
rce
nta
ge
of
pa
tie
nts
(%
)
Annoyance Disturbance
Day time
Night time
Figure 11.7 Overall percentages of patient annoyed / disturbed by noise
Patients were also asked if they ever found it too quiet in the ward. Out of 154 respondents, only 9
patients said this was the case. Room data was only available for six of these respondents, with two
in a single room and four in either four or six bed bays.
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11.3.2. Patient gender
Figure 11.8 shows the mean perceptions of day and night time noise by male and female patients on
a scale of 1 to 5, where 1 indicates ‘very quiet’ and 5 indicates ‘extremely noisy’. It can be seen that
the average perception of day time noise is identical for both male and female patients (mean value of
2.5), however, male patients appear to perceive the wards to be noisier at night, whereas female
patients perceive the levels to be similar to those during the day. It should be noted that apart from
the average male perception of 3.5 at night (slightly noisy to noisy), the average ratings are around
2.5 (quiet to slightly noisy).
1
2
3
4
5
Male (n=92) Female (n=62)
Me
an
pe
rce
pti
on
of
no
ise
lev
el
(1=
ve
ry q
uie
t /
5=
ex
tre
me
ly n
ois
y)
Patient gender
Day time
Night time
Figure 11.8 Mean patient perception rating of noise by gender
Figure 11.9 shows the percentages of patients by gender that are annoyed or disturbed by day and
night time noise. It can be clearly seen that similar percentages of both male and female patients are
annoyed by noise during the day, which agrees with the perception of the noise climate during the day
as shown in Figure 11.8. However, it is interesting to note that during the night, slightly more women
(55%) than men (51%) are disturbed by noise. This is in contrast to the night time perception, as
shown in Figure 11.8, which shows that women perceive the ward to be quieter at night than men.
0
20
40
60
80
100
Male (n=92) Female (n=62)
Pe
rce
nta
ge
s o
f p
ati
en
ts a
nn
oy
ed
/ d
istu
rbe
d (
%)
Patient gender
Day time annoyance
Night time disturbance
Figure 11.9 Percentages of patients annoyed / disturbed by noise by gender
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11.3.3. Age
This section examines the effects of age on patient perceptions of noise, and on annoyance and
disturbance. Figure 11.10 shows that perceptions of day time noise are found to be very consistent
across all age ranges, with mean values between 2.4 and 2.6, suggesting that patients of all ages
gauge the noise climate to be in the range ‘quiet’ to ‘slightly noisy’ during the day. However, the
perception of noise at night appears to be more variable, with two age groups perceiving slightly
noisier conditions: the under 20’s (mean value 2.8); and those in the 41-50 age group (mean value of
3.1). Patients in the age groups 31-40, 51-60 and 60+ appeared to perceive the conditions similarly,
with those in the 20-30 age bracket perceiving the wards at night to be the quietest (mean value of
1.9). It can also be seen that the perception of noise on the ward during the night is generally lower
than it is during the day, except in age groups under 20 and 41-50 years.
1
2
3
4
5
<20 20-30 31-40 41-50 51-60 60+
Me
an
pe
rce
pti
on
of
no
ise
lev
el
(1=
ve
ry q
uie
t /
5=
ex
tre
me
ly n
ois
y)
Age group (years)
Day time
Night time
(n=8)(n=16)
(n=19)
(n=22)
(n=84)
Figure 11.10 Mean rating of patient perceptions of day and night noise and age
Noise annoyance / disturbance and age group is shown in Figure 11.11. It can be clearly seen that
patients in the age groups 31-40 and above are more disturbed by noise at night than during the day;
which is in contrast to many of the perceptions shown in Figure 11.10. Patients in the 41-50 age
group appear to be more disturbed by night time noise than those in any other age group (74%),
followed by the 51-60 age group (61%). This could be due to independent lives led by the individuals
in these groups and levels of control they are used to having within their lives.
(n=5)
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0
20
40
60
80
100
<20 20-30 31-40 41-50 51-60 60+
Pe
rce
nta
ge
s o
f p
ati
en
ts a
nn
oy
ed
/ d
istu
rbe
d (
%)
Age group (years)
Day time
Night time
(n=8)
(n=16)
(n=19)
(n=22)
(n=84)
(n=5)
Figure 11.11 Percentages of patients annoyed / disturbed and age
11.3.4. Hearing impairment
26% of respondents indicated that they suffered from a hearing impairment of some kind. This could
include many different conditions such as hearing loss; increased sensitivity at particular frequencies
and tinnitus. Figure 11.12 shows the breakdown of hearing impairment by patient age. It can be seen
that out of those suffering from some type of hearing impairment, 75% are over years 60 years of age.
This may account for the lower perceptions of the noise climate by this age group (shown in Figure
11.10)
0
10
20
30
40
50
60
70
80
<20 20-30 31-40 41-50 51-60 60+
Pe
rce
nta
ge
of
he
ari
ng
im
pa
ire
d (
%)
Age group (years)
Figure 11.12 Percentage of hearing impaired by age group
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To see if hearing impaired patients were any less annoyed or disturbed by noise, percentages of
annoyance and disturbance are plotted against hearing impaired / non hearing impaired patients, as
shown in Figure 11.13. In terms of annoyance 7% fewer hearing impaired patients indicated they
were annoyed by day time noise than the non hearing impaired, with 3% fewer patients indicating that
they were disturbed at night.
0
20
40
60
80
100
Hearing impaired No impairment
Pe
rce
nta
ge
of
pa
tie
nts
an
no
ye
d /
dis
turb
ed
(%
)
Day time annoyance
Night time disturbance
Figure 11.13 Percentage of patients annoyed / disturbed with hearing impairment
Speech intelligibility and perception of speech privacy were also examined for differences between
the hearing impaired patients and non hearing impaired. In terms of speech intelligibility, 35% of
hearing impaired patients felt they could not always hear when staff spoke to them, in contrast to 82%
of patients without any impairment. Little difference was found in terms of conversational privacy, with
69% of patients with a hearing impairment feeling that they could carry out a private conversation on
the ward, and 65% of those without a hearing impairment feeling the same.
11.3.5. Length of stay
Length of patient stay has been investigated to see whether there is a difference in perceptions of
noise and annoyance and disturbance between short term and longer term patients. Figure 11.14
shows mean perceptions of day and night time noise for patients who have been in hospital for less
than 1 week, between 1 and 3 weeks and for more than three weeks. Responses are very consistent
for patients who have been on the ward for up to three weeks. Longer term patients, however, appear
to perceive day time noise levels very slightly higher and night time noise levels slightly lower.
Perhaps this in an indication that longer term patients manage to acclimatise to the noise of the ward
at night. However, it should be noted that the sample size for patients who had been on the ward for
over three weeks was comparatively small (n=14).
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1
2
3
4
5
< 1 week 1 - 3 weeks > 3 weeks
Me
an
pe
rce
pti
on
of
no
ise
lev
el
(1=
ve
ry q
uie
t /
5=
ex
tre
me
ly n
ois
y)
Length of patient stay
Day time
Night time
(n = 96)(n = 44)
(n = 14)
Figure 11.14 Mean rating of patient perceptions of day and night noise and length of stay
Figure 11.15 shows the percentages of patients annoyed / disturbed by noise in relation to length of
stay. It can be seen that 20% of patients who had been on the ward for less than one week, and 19%
of patients whose stay was one to three weeks indicated they were annoyed by day time noise.
However, this percentage more than doubled for longer term patients, with 43% annoyed by noise
during the day. This trend was reversed for night time disturbance, with only 36% percent of long term
patients expressing night time disturbance in comparison to those patients who had been on the ward
for less time. Again, as with the noise perception, this response suggests a certain amount of
acclimatisation to the night time noise climate by longer term patients, but more sensitivity to noise
during the day.
0
20
40
60
80
100
< 1 week 1 - 3 weeks > 3 weeks
Pe
rce
nta
ge
of
pa
tie
nts
an
no
ye
d /
dis
turb
ed
(%
)
Length of patient stay
Day time annoyance
Night time disturbance
Figure 11.15 Percentages of patients annoyed / disturbed and length of stay
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11.3.6. Bed position
In general beds are only specifically allocated to either infectious patients who require barrier nursing
(these patients may be placed in a single room); on the basis of gender (if no same sex
accommodation is available patients may be placed in a single room); or if the patient is very unwell
and requires observation (the patient may be placed in the bay nearest to the nurse station).
This section investigates whether there are any relationships between noise annoyance / disturbance
and bed position, with positions defined as ‘next to the ward corridor’, ‘in the centre of the bay’, ‘by the
window’, or in ‘a single patient room’. Figure 11.16 shows the percentages of patients annoyed /
disturbed in each type of bed location. It can be seen that surprisingly, the highest percentages of
patients reporting daytime annoyance and night time disturbance are those staying in single rooms,
with 50% and 58% reporting annoyance and disturbance respectively. Percentages of patients in
multi-bed bays reporting daytime annoyance are much lower, between 17% and 24%, with those by
the window reporting slightly lower levels of annoyance. Percentages of patients reporting night time
disturbance are similar in all cases except for those patients in beds by the window, where 10% fewer
respondents report disturbance.
It is interesting that the lowest levels of annoyance / disturbance are reported by patients in beds
located by windows. This is a similar finding to that by Yildirim et al (2007), who observed that for
office workers, being positioned by a window compensated for some of the negative perceptions of
open plan offices, such as low levels of visual or acoustic privacy.
0
20
40
60
80
100
Corridor Window Middle Single room
Pe
rce
nta
ge
of
pa
tie
nts
an
no
ye
d /
dis
turb
ed
(%
)
Bed position on ward
Daytime annoyance
Night time disturbance
(n=9)
(n=54)
(n=12)(n=18)
Figure 11.16 Percentages of patients annoyed / disturbed and bed position
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11.3.7. Speech intelligibility and privacy
Speech intelligibility on the wards is extremely important to enable clinical staff and patients to be able
to discuss issues surrounding the patient’s condition and their treatment without the loss of important
information. Speech intelligibility was not measured objectively during this study, but was gauged in
part by asking patients if they could always hear clearly when the doctors and nurses spoke to them,
which overall 69% of respondents said that they could. The relationship between speech intelligibility
and the size of the bay was investigated by averaging the number of people who said they could
always hear clearly. No relationship between was found, with a low correlation coefficient (ρ=.333,
ns). The perceptions of speech intelligibility among hearing impaired patients was also investigated
and discussed in Section 11.3.4.
In recent times there has been much publicity surrounding poor conversational privacy on hospital
wards. To investigate this, patients were asked if they felt able to hold a private conversation with
clinicians at their bedside. The responses in relation to the bay size are shown in Figure 11.17. It can
be seen that 100% of patients in single rooms felt that they could hold private conversations. This is
unsurprising as these patients have the option to close the door to their room if necessary. Between
60% and 68% of patients on wards with four or more beds felt that they could hold private
conversations, with only 40% of patients in three bed bays feeling they could. The relationship
between conversational privacy and the size of the bay was investigated by averaging the number of
people who found conversational privacy to be acceptable. There was not a significant correlation
found between ward size and conversational privacy (ρ= -.322, ns).
0
20
40
60
80
100
1 3 4 6 7 12
Pe
rce
nta
ge
of
pa
tie
nts
wh
o f
elt
th
ey
co
uld
ho
ld a
pri
va
te
con
ve
rsta
ion
(%
)
Bay size (number of beds)
Figure 11.17 Patient privacy and bay size
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11.4. Factors affecting staff perceptions of noise
This section considers the responses of staff on the main study wards in Bedford and Addenbrooke’s
Hospital. Sources of noise annoyance and interference to staff were examined in detail in Chapters 7
and 9 in relation to each study ward. As with patient perception, these sources were found to be ward
specific and so to look for general trends in this data would not be appropriate. This section looks
further at more general relationships including whether gender, age, and length of service increase
feelings of noise annoyance and noise interference in relation to work.
11.4.1. Overall
Figure 11.18 shows the perceptions of day and night time noise for all 66 staff respondents. It can be
seen that the highest percentage of staff (25%) cite levels of annoyance and interference as ‘slight’,
with 18% moderately annoyed by noise. Higher levels of annoyance are cited by only nine staff in
total (13%), with eight choosing ‘very noisy’ and one selecting ‘extremely’.
0
5
10
15
20
25
30
Not at all Slightly Moderately Very much Extremely
Pe
rce
nta
ge
of
sta
ff (
%)
Staff annoyance and interfernce levels
Annoyance
Interference
Figure 11.18 Staff levels of annoyance and interference
11.4.2. Gender
Figure 11.19 shows the average feeling of noise annoyance and noise interference with work by staff
gender. It can be seen that the average level of annoyance and interference on the ward is higher for
male staff, however all ratings are fairly low in the range ‘slightly’ to ‘moderately’ for both men and
women. Noise annoyance is rated consistently higher than interference with work by both male and
female staff.
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1
2
3
4
5
Male Female
Lev
el o
f n
ois
e a
nn
oy
an
ce /
inte
rfe
ren
ce
(1=
no
t a
t a
ll /
5=
ex
tre
me
ly)
Staff gender
Noise annoyance
Noise interference
(n=13)
(n=54)
Figure 11.19 Level of noise annoyance / interference by staff gender
11.4.3. Age
The next section considers whether the age of the staff member is related to the level of noise
annoyance / interference they perceive in their working environment.
1
2
3
4
5
<20 20-30 31-40 41-50 51-60
Lev
el o
f n
ois
e a
nn
oy
an
ce /
inte
rfe
ren
ce
(1=
no
t a
t a
ll /
5=
ex
tre
me
ly)
Age group (years)
Noise annoyance
Noise interference
(n=11)
(n=3)
Figure 11.20 Level of noise annoyance / interference by staff age
It can be seen in Figure 11.20 that it is the younger members of the staff and the older staff who
appear to have more extreme views. Staff under 20 years old appear to be untroubled by noise while
(n=3)
(n=34)
(n=16)
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those in the 51-60 age group rate noise annoyance and interference more highly than any other age
group (with a mean of 3.0 for both annoyance and interference). However, it should be noted that the
sample sizes for both these age groups are very low (n=3). Statistically, no relationship was found
between levels of annoyance and age (ρ= -.262, ns), or levels of interference and age (ρ= -.16, ns).
11.4.4. Time worked on the ward
The relationship between length of time worked on the ward and level of noise annoyance / noise
interference is illustrated in Figure 11.21. It can be seen that in all cases the feelings of annoyance
and interference are fairly low, predominantly in the range ‘slightly’ to ‘moderately’, with both new staff
and staff in the 4-5 year bracket reporting very low levels. Although ratings increase for the first three
years, this is not a constant trend overall. One interesting point to note is that staff who have worked
on the ward for over five years rate interference with work more highly than annoyance, in contrast to
all the other time brackets.
1
2
3
4
5
<1 year 1-2 years 2-3 years 3-4 years 4-5 years 5+ years
Lev
elo
f n
ois
e a
nn
oy
an
ce /
inte
rfe
ren
ce
(1=
no
t a
t a
ll /
5=
ex
tre
me
ly)
Time worked on the ward
Noise annoyance
Noise interference
(n=30)
(n=8)(n=9) (n=4)
(n=3)
(n=11)
Figure 11.21 Level of noise annoyance / interference by time worked on the ward
No statistically significant relationship exists between time worked on the ward and annoyance ratings
(ρ=.16, ns), and time worked on the ward and interference ratings (ρ=.29, ns).
11.4.5. Time worked at the hospital
The relationship between length of time worked at the hospital and levels of noise annoyance / noise
interference is illustrated in Figure 11.22. It can be seen that in most cases the feelings of annoyance
and interference are fairly low, predominantly in the range ‘slightly’ to ‘moderately’, with those new
staff and staff in the 3-4 and 4-5 year brackets reporting very low levels. Although levels increase for
the first three years, this is not a constant trend overall. As with time worked on the ward, staff who
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have worked in the hospital for over five years rate interference with work more highly than
annoyance; in this case in the ‘moderately’ to ‘very much’ range.
Statistically, there is no significant relationship between time worked at the hospital and annoyance
and interference ratings (ρ= .16, ns and ρ= .29, ns respectively).
1
2
3
4
5
<1 year 1-2 years 2-3 years 3-4 years 4-5 years 5+ years
Lev
el o
f n
ois
e a
nn
oy
an
ce /
inte
rfe
ren
ce
(1=
no
t a
t a
ll /
5=
ex
tre
me
ly)
Time worked at the hospital
Noise annoyance
Noise interference
(n=21)(n=9)
(n=7)
(n=3)
(n=24)
Figure 11.22 Level of noise annoyance / interference by time worked at the hospital
11.4.6. Relationship between noise annoyance and noise interference
Considering the overall data set of 66 responses, the relationship between noise annoyance and
noise interference was investigated. A statistically significant correlation between annoyance and
interference ratings was found (ρ= .730, p=0.01). This suggests that staff rating noise annoyance
highly will also rate noise interference highly. If this is the case, it is possible that posing a single
question on noise annoyance / interference would be sufficient to provide the information required.
11.5. Discussion
Analysis of the overall dataset on noise and patient and staff perceptions has yielded some interesting
and surprising results.
It has been shown that the size of a bay is not related to the noise levels in the bay during the day or
at night, with some of the highest levels measured in single rooms and in three and four bed bays.
Overall measured noise levels in a medical and surgical ward at the same hospital were found to be
similar; however the content of the noise and the perceptions of the staff and patients differed. In the
busier surgical ward, visiting time, the internal telephone, meal times, the nurse call, and trolleys were
(n=2)
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all found to cause more interference to the work of the staff. Patients on the medical ward found the
crying out of other patients caused a great deal of annoyance and disturbance, whereas patients on
the surgical ward rated trolleys and the nurse call more highly.
The average number of high level noise events (greater than 70 dB LAmax) were shown to be strongly
correlated to overall measured noise levels both day and night. Analysis suggests that the impact of
high level noise events on night time levels is considerably greater than during the day, as the
increase of day time ambient levels provide a certain amount of masking. This suggests that patients
would experience greater disturbance by high level noise events during the night.
Noise levels have been shown to be directly related to RT, with lower noise levels corresponding to
lower RTs, as expected. Analysis has found that for every 0.1 s decrease in the RT, there is a
decrease in the average day time noise levels of 1.2 dB LAeq,16hr . This confirms the relationship that is
illustrated by the ceiling intervention study in Chapter 8, where the addition of an acoustically
absorbent ceiling was found to decrease both RTs and overall noise levels.
The perception of the noise climate by male and female patients was found to differ, with male
patients perceiving a noisier environment during the night than female patients. However, annoyance
and disturbance ratings were the same for both genders.
Patients whose stay on the ward was less than three weeks perceived the noise climate on the ward
to be similar both day and night, however they were more disturbed by night time noise than longer
term patients (> 3 weeks). However, longer term patients appeared to be more annoyed by day time
noise than shorter term patients but were less sensitive to noise during the night. This suggests a
certain amount of acclimatisation to noise on the ward at night.
Differences in noise perception and annoyance were found between patient age groups. In terms of
perception, day and night levels were generally perceived similarly and were fairly low, in the ‘quiet’ to
‘slightly noisy’ category, with patients in the 41-50 age group at night time having the worst
perceptions of the noise environment, with an average rating of 3.2. In terms of annoyance and
disturbance it was found that patients in the age groups 31-40 and above were much more disturbed
by noise at night than during the day, with the highest percentage again in the 41-50 age group
(74%). Perhaps this is an indication of the higher expectations of those patients in this particular age
bracket.
Patients staying in a single room were found to be more annoyed by noise than those in multi-bed
bays, with 50% and 58% of single room patients reporting day time annoyance and night time
disturbance respectively. Day and night time levels reported by patients in a multi-bed bay were
found to be considerably lower during the day (20%) and slightly lower at night (53%). It was found
that patients in beds situated by the window reported lower rates of day time annoyance and night
time disturbance (17% and 47% respectively) than patients in other bed locations.
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Satisfactory conversational privacy was reported by all patients in single rooms, and by similar
percentages, 63% on average, of those in bays of four to twelve beds. Interestingly only 40% of
patients in three bed bays felt that they could speak privately.
Little difference was found in terms of noise annoyance and disturbance and conversational privacy
between those patients with a hearing impairment and those without.
Levels of noise annoyance and interference rated by staff were generally found to be low, in the most
part in the ‘slightly’ to ‘moderately’ range. In terms of staff gender, male staff rated noise annoyance
and interference slightly higher than female staff and in relation to age, the youngest members of the
staff and the older staff had more extreme views. Staff under 20 years old appeared to be untroubled
by noise, with those in the 51-60 age group rating noise annoyance and interference more highly than
any other age group. However, even in this case it must be stressed that the mean rating of 3.0 is not
particularly severe.
No significant relationship was found between staff attitudes to noise and either the length of time
they had worked on the ward or the length of time they had worked at the hospital. The main
difference was in the ‘5+ years’ bracket in both categories, where staff rated noise interference with
work more highly than noise annoyance. Perhaps this is related to the changes that these staff have
seen over many years in relation to additional noise sources, for example, the more prevalent use of
ward equipment with alarms, and it may be an indication of the worsening noise climate in hospitals.
11.6. Conclusions
The main conclusion of this chapter is that, contrary to current thinking, single bed rooms are not
quieter than multi-bed bays. This has been shown both objectively, from the measured noise level
data, and subjectively from patient perceptions of noise. This is an important finding given the current
thinking and the preference for providing more single rooms in hospital wards.
The results also highlight the need to reduce RTs in hospital wards in order to decrease the overall
noise levels.
Other points to note are that there is some evidence that longer term patients acclimatise to noise at
night, but become more annoyed by noise during the day time; and that consideration needs to be
given to the issue of speech privacy and how it may be improved, particularly in 3-bed bays.
The following chapter looks at ways of controlling hospital noise using a multi-faceted approach. The
validity of relevant standards is discussed and acoustic reporting metrics are also explored.
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12. Noise control in inpatient care
12.1. Introduction
This study has shown that the problem of hospital noise is very complex in nature, with many different
factors affecting the noise climate. This was also found to be the case in the previous research on this
topic. It is felt that if any significant improvement is to be achieved, a multi-faceted approach is
required, which should be centred on three main areas:
� Optimising the acoustic design of the ward
� Minimising the disturbance caused by equipment in use on the ward
� Modifying the behaviour of those on the ward
This chapter discusses each of these areas in detail in relation to the findings from the current study.
Validity of relevant standards and reporting metrics are also explored.
12.2. Optimising the acoustic design of the ward
This study focuses on a number of areas of acoustic design, including whether the design for infection
control purposes has compromised ward acoustics; the effects of adding acoustic absorbency; and
the impact of the ward design and building construction on the noise climate. These areas are
considered and discussed further in the following section.
12.2.1. Design for infection control
One of the aims of the study was to investigate whether the design of a hospital building for infection
control purposes was detrimental to the acoustic design. Three of the study wards which were built in
the last decade, a time when concerns over infection control were being considered carefully in terms
of building finishes. The study found that in each of the wards, suspended ceilings with good quality
acoustic tiles were installed throughout all patient accommodation, and in some instances in the
common areas. Reverberation times in all the areas with acoustic tiles were found to be very low.
The use of acoustic tiles in these new buildings is largely due to the efforts of the acoustic product
manufacturers, who have responded positively to infection control concerns by developing a number
of different ceiling tiles specifically for use in healthcare buildings, and thus ensuring that the acoustic
design of the wards is not compromised. Tiles are now available which can withstand cleaning using
strong disinfectants, or even steam cleaning. Specific tiles have even been produced that are treated
with antimicrobial agents, preventing any bacteria from growing on their surface.
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12.2.2. The effects of adding acoustic absorbency
The latest acoustic design guidance, HTM 08-01: Acoustics (The Stationary Office, 2008), suggests
that the most appropriate area for acoustically absorbent material should be a ceiling, with the
minimum absorption area equivalent to 80%. The beneficial effects of installing an acoustic ceiling are
illustrated by the ceiling intervention study, which was discussed in Chapter 8, and showed a
reduction of 0.15 s in reverberation time (RT) and 2.4 dB in noise level.
The relationship between RT and noise levels is discussed further in Section 11.2.3, which shows a
statistically significant relationship between day time RT estimates and daytime LAeq,16hr (ρ=.498,
p<0.05). It is shown that for every 0.1 s decrease in the RT, there is a decrease in the average day
time noise levels of 1.2 dB LAeq,16hr. This is reasonably consistent with the findings of the ceiling
intervention study.
These findings stress the importance of installing an acoustically absorbent ceiling in hospital wards.
12.2.3. Ward design
The five main study wards were all designed around a long central corridor, with patient
accommodation generally situated on one side, and healthcare resources on the other. The pilot
study ward was based on a ‘racetrack design’ with patient accommodation situated on the outside of
the building, and healthcare resources in the centre. Objective and subjective data from the study
suggests that the most important aspect to be considered in terms of ward layout is not the overall
design, but the positioning of patient accommodation in relation to the healthcare utilities. Careful
thought must be given to ensure that there are no direct sound paths from potentially noisy areas to
patient accommodation. The two study wards in Bedford Hospital provide several examples of where
poor positioning of patient accommodation leads to annoyance and disturbance of patients, and are
discussed below.
� The kitchen, ward clerk’s desk and staff room are all situated directly opposite a multi-bed bay
in the two study wards. All these areas are potentially noisy, with bangs and crashes often
heard from the kitchen area, and conversational noise heard from the staff room and at the
ward clerk’s desk. Objective and subjective results both indicate that noise from these areas
has a detrimental effect in terms of noise levels and patient annoyance and disturbance in the
bay opposite.
� Two single rooms are positioned directly behind the main nurse station in both wards.
Objective and subjective results again indicate that patients in these rooms are adversely
affected by noise from activity at the nurse station: with staff conversation; the nurse call; and
general activity clearly audible.
Not only is thought required in the siting of patient accommodation, but care must also be taken in
ensuring that areas that require easy access by staff are designed as such. One particular example of
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impractical design is found in Ward N3 at Addenbrooke’s Hospital. Here, a number of rooms are
situated close to the nurse station, including the clean and dirty utility rooms, and a general
storeroom. None of these rooms contain anything requiring secure storage, but for some reason all
doors to these rooms have been fitted with security access via a key code pad. Staff entering these
rooms often have their hands full, and so to overcome the need to input the security code, the doors
to these rooms are all left on the latch. Unfortunately, this has a negative impact on the noise
environment as the doors literally bounce when shutting, causing a loud bang. In fact this noise
accounted for 48% of the total number of trigger files captured during the measurement period in this
location, with levels consistently measured at 79 dB LAmax.
One issue highlighted by the study is that of ‘open door nursing’, which is still used by clinicians in UK
hospitals today. The study found that the staff have been trained to carry out their nursing duties with
doors to the patient bays and single rooms left open at all times for observation purposes. The only
exception to this is if barrier nursing is required, and then doors to a single room may be closed.
Several sections in the latest acoustic healthcare design guidance HTM 08-01 (The Stationary Office,
2008) advise on levels of noise attenuation between rooms, and of the type and properties of suitable
acoustic doors to be installed on the wards. It is considered extremely important that an
understanding of the way the building will be used when occupied is considered when specifying the
acoustic design. Considerable expense may be incurred in relation to the installation of acoustic doors
and sound attenuating material, when in reality they will be of no actual benefit, as the staff will leave
the doors to the patient accommodation open.
12.2.4. Building construction
The majority of the ward buildings in this study are primarily of concrete construction, with concrete
floors, suspended ceilings, and stud or block partitions. As this study is concerned with occupied
buildings, it has not been possible to view the building construction as a singular entity. However,
subjective responses have provided clues as to areas within the building construction that may cause
annoyance to staff and patients. These areas are discussed below.
� The mechanical ventilation system was cited by ward staff in Sky Ward, GOSH. The installed
system is centrally controlled, but air flow was found to be noticeably different in some areas
of the ward, with some patient accommodation and staff offices adversely affected by noise
and heat from the system.
� At Bedford Hospital, where wards are naturally ventilated, annoyance and disturbance to
patients due to external noise increased during the summer months, when the windows were
open, with 37% of patients citing external noise as a night time disturbance. This appeared to
be a less of problem in the cooler months, with lower percentages of patients (13%)
disturbed.
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� Single glazing also accounted for additional disturbance by external noise, as discussed in
Section 7.9.2. However, it is interesting to note that patient opinions were split, with some
finding the lack of attenuation by the single glazed unit to be annoying, but with others finding
the connection with the outside world beneficial.
Careful consideration needs to be given to the choice of mechanical and / or natural ventilation, as
both have their own inherent problems.
One study ward is of a very different construction and this is worth discussing in further detail. Ward
N3 is a modular ward at Addenbrooke’s Hospital and is of mainly timber construction. This block was
opened in 2009 and was built to comply with acoustic standard HTM 2045. It has a good quality
acoustic ceiling and all room partitions are sound insulated, but it is the floor that is of interest. When
the ward first opened, the springy nature of this floor generated many complaints from staff, who
found it detrimental to their feet. Remedial work was carried out to further stiffen the floor, and
although improved, the floor does appear to have a negative effect on the noise climate, by
magnifying certain sounds. Groups of people walking past the nurse station were found to generate
noise levels exceeding 70 dB LAmax, a footfall noise level not found on any other study wards. This
was confirmed by questionnaire responses, where 40% of ward staff claimed they found the sound of
footsteps annoying, and 20% of patients cited footsteps as a night time disturbance. These
percentages are the highest found in relation to annoyance and disturbance from footsteps on any
study ward. The noise of trolleys also appears to be exacerbated by the timber floor construction, with
40% of patients citing trolleys as a source of annoyance.
Care should be taken when choosing the type of floor construction for use in hospital wards, as the
use of a timber floor can exacerbate noise levels and is found by staff cause discomfort.
12.2.5. Building age and overall noise levels
The age of the hospital buildings included in the study varied from less than ten years to around 40
years, with some new build (within the past ten years) and others built in the 1970’s and 1980’s. The
1970’s ward lacked space, having a larger number of beds than it was originally designed for (as
discussed in Chapter 9.3.1) and the largest bay sizes of all the study wards. Occupied RTs were
found to be slightly higher than the newer wards with acoustic ceilings, but these values were still
relatively low (ranging from 0.4 s to 0.6 s at 1 kHz). The 1980’s wards were single glazed, which
accounted for additional disturbance by external noise, as discussed in the previous section. The
positioning of patient accommodation in relation to the kitchen, ward clerk’s desk and nurse station
was also found to be detrimental to noise levels. Buildings constructed in the last ten years were
found to have good quality acoustic ceilings and very low reverberation times (for example, less than
0.3 s at 1 kHz in Ward N3). Wards were generally found to be much more spacious, with wider
corridors, plenty of equipment storage and improved bed spacing.
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Figure 12.1 shows the day time noise levels (LAeq,16hr) measured in the patient accommodation
grouped by building age. It can be seen that with only one exception, overall measured LAeq,16hr values
lie within a 10 dB band, between 50 and 60 dB LAeq,16hr. A statistically significant correlation was found
between building age and overall day time noise levels (ρ= -.589, p=0.01), suggesting that newer
buildings are quieter.
0
10
20
30
40
50
60
70
1970's 1980's 2000's
LA
eq
, 16h
r (d
B)
Decade in which building comissioned
Figure 12.1 Average day time levels by building age for all patient accommodation
Figure 12.2 shows the night time noise levels (LAeq,8hr) measured in the patient accommodation
grouped by building age. It can be seen that all overall measured LAeq,8hr values lie within a 10 dB
band, between 41 and 51 dB LAeq,8hr. In the case of night time noise levels and building age no
significant relationship was found (ρ= -.348, ns). However, the negative correlation coefficient
indicates a trend for the overall noise levels to decrease in the newer buildings as with the daytime
levels.
0
10
20
30
40
50
60
70
1970's 1980's 2000's
LA
eq
, 8h
r (d
B)
Decade in which building commissioned
Figure 12.2 Average night time levels by building age for all patient accommodation
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12.3. Ward equipment
The study shows that the cacophony of alarms and tones emitted by the electronic equipment in use
on the ward is becoming a major source of noise. Items such as nurse call systems, internal
telephones and medical equipment occur frequently and were found to generate high noise levels,
with some alarms left for some time before they are reset. These types of systems are continually
cited by staff and patients as sources of annoyance and disturbance.
The poor design and maintenance of other types of ward equipment is also found to contribute to high
levels of noise, and is discussed further in this section, with possible noise control measures
suggested where appropriate.
Following the pilot study carried out at GOSH, follow up meetings were held with staff to discuss the
results of the study and possible improvements that could be made to the noise environment. Where
appropriate the feedback from these meetings is incorporated into the following sections.
12.3.1. Nurse call systems
In preliminary discussion with ward managers, the nurse call was cited as a source of annoyance, and
this was supported by the questionnaire responses from staff on all the study wards. In some
instances annoyance was related to correspondingly high noise levels, for example a level of 72.7 dB
LAmax was measured at the nurse station in the surgical ward at Bedford Hospital.
Some of the nurse call annoyance was due to the level of the noise emitted by the system. In several
cases it was found that the day and night volume settings, which were meant to change the volume
level, appeared to be faulty, with no difference found in the volume of the tone emitted. In other cases
the volume was simply too loud and not adjustable. Unfortunately, although annoying this did not get
logged as no clear reporting structure appeared to be available for issues of this nature.
Commissioning of the system also appeared to be at fault on occasion, with staff finding that the
system was not performing as they would wish in terms of functionality. Staff in one particular study
ward commented that they were not able to hear the nurse call if they were attending to a patient in a
different bay, and this made it hard to carry out their nursing duties effectively.
12.3.2. Internal telephones
As with the nurse call system, the internal telephone was cited as a source of annoyance and
interference by staff, and as a disturbance by patients. Comments made suggest that one of the main
issues is not about the volume of the ring tone, but the length of time the phone rings before being
answered.
In all study wards there are a number of wired, static phones on desks. In some cases these are used
alongside personal paging systems. Given that the majority of people own mobile telephones which
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have silent, vibrating functionality, surely the ringing desk phone is an unnecessary object in any
hospital ward?
In a post study meeting with staff from the pilot study ward at GOSH, a number of interesting points
were made regarding telephone use on the ward. These are detailed below.
� The responsibility of the ward clerk on this ward is to act as a first point of contact for external
telephone calls. When away from her desk, which is a regular occurrence, unanswered
telephone calls are redirected through to the ward to be answered by a member of the clinical
staff. This of course wastes the clinicians’ time, as they then have to take a message back to
the ward clerk’s desk. It was suggested that by simply installing a voice mail system many of
these unnecessary calls could be dealt with automatically. This idea was positively received
by all staff and has been implemented.
� Some newer staff members commented that they were not aware of how to turn down volume
levels of the telephone ring tones. This suggested a possible issue with the training of new
staff.
� A new CISCO system is currently being trialled in another ward at GOSH which uses internet
technologies. The system uses wireless telephones which are given to each member of staff
and could potentially replace all existing telephones and paging systems, and the nurse call.
Staff felt that if implemented, this system would be beneficial.
12.3.3. Medical equipment alarms
Medical equipment alarms were also one of the major sources of annoyance to both staff and
patients, with the alarms emitted often loud, and on occasion seemingly unnecessary. One example
captured during the study was that of a patient monitor which bleeped at a level of 75 dB LAmax every
30 seconds for two and a half hours in a single room. This would surely have disturbed the patient,
who would have been trying to rest, and must surely warrant the question: if this did not require
intervention, then why was there a tone emitted at all?
It is possible that the setup of many pieces of medical equipment is so complex that once they are
commissioned, the settings are never changed. For example, one particular ECG machine identified
had a total of 16 different settings. Again this suggests that there should be some collaboration
between the staff who use these pieces of equipment and the installer and / or manufacturer.
Continued staff training may also be an issue. It is possible that when first installed, staff on the ward
are provided with the necessary training on how to tailor a piece of medical equipment to their own
requirements. However, with the extremely high turnover of staff in healthcare and the regular use of
temporary agency staff, this knowledge may be lost relatively quickly. Perhaps follow on training
should be provided periodically, or staff should be issued with necessary information on induction.
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12.3.4. Doorbell
The pilot study ward at GOSH and each study ward at Addenbrooke’s Hospital could only be
accessed using a security pass. For visitors to announce their arrival at the ward entrance, a doorbell
was installed. These doorbells cause a great deal of annoyance and interference to staff not only due
to the volume, which has been measured at levels as high as 80.6 dB LAmax in one case, but with
visitors constantly pushing the buzzer until the entrance door is opened. Staff felt that visitors did not
appreciate that they may be busy on the ward and could not simply ‘drop everything’ to answer the
bell.
In the post study meeting with staff at GOSH it was felt that limiting the number of times the doorbell
rang to once every 30 seconds would help a great deal in alleviating this annoyance. Staff also felt
that somehow setting ward visitors’ expectations regarding the length of time it may take to answer
the door might also help, perhaps using something as simple as a clear written notice on the entrance
door.
12.3.5. Rubbish bins
Rubbish bins on several of the study wards were found to cause annoyance and disturbance to
patients, and high levels of noise. Although many of the bins in use have been specifically designed to
have quiet closing lids, they are often positioned too close to a sink or wall. On opening, the lid hits
the nearby surface or object, causing a loud bang and entirely defeating the point of the quiet closing
mechanism. The body of the bin is also a problem, as it is generally solid and undamped; hence
discarding a heavy object also causes noise.
Design improvements have been made to rubbish bins, with the addition of quiet closing mechanisms,
however the correct siting of the rubbish bin is imperative; wall spacers and some additional damping
in the body of the bin would alleviate much of this unwanted noise.
12.3.6. Ward furniture
Furniture scraping on the floor was found to be a source of high level noise in several study wards.
This could be simply and cheaply controlled by fitting rubber feet or wheels to the chairs and other
furniture used.
12.3.7. Wheeled equipment
Much of the equipment used on the wards has wheels to allow for portability. This includes patient
beds, ward furniture, medical equipment, as well as the standard ‘trolleys’ used to deliver meals,
drinks, medication, linen and other supplies. Noise from trolleys has been measured at levels as high
as 85 dB LAmax, which is due to in part to inherent flaws in their design. Many of these pieces of
equipment are metal; have no damping; and have ill-adjusted wheels and unsuitable tyres.
It is interesting to note that the Ministry of Health Hospital Design Note 4: Noise Control (Her
Majesty’s Stationery Office, 1966) recognised trolleys as a major source of noise, recommending that
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good quality rubber tyres be fitted. It is very sad to think that 45 years later, these inherent design
flaws have not been improved.
12.3.8. Ring binders
In all the study wards, patient notes and other reading materials are stored in ring binders. Without
exception the clicking shut of these ring binders was captured at high levels and on numerous
occasions during the study, with measured levels as high as 85 to 90 dB LAmax. Often these levels
were captured at a nurse station during the night, when nursing staff were catching up on
administrative tasks. It is thought that other types of folder could easily be sourced which do not make
use of the ring binder spring loaded mechanism and therefore do not cause unnecessary disturbance
to those patients close by, who may be asleep or trying to sleep.
12.3.9. Doors
Banging doors were cited as disturbing in a number of the study wards and this could be simply
remedied by fitting or adjusting quiet door closers, or in the case of metal cupboards, installing some
damping.
One occasion of poor workmanship was discovered in relation to a heavy fire door. Although the quiet
closer was working correctly, the door frame was too large and on closing the door would rattle loudly,
the sound carrying down the main ward corridor.
Whether due to poor maintenance, lack of a quiet door closer or poor workmanship, all these
problems are relatively cheap to fix. However, what appears to be unclear is the reporting mechanism
for staff to log a fault of this nature. An example of this is illustrated in the pilot study ward at GOSH.
Staff here became so irritated with doors banging that they took matters into their own hands and
draped towels over the doors to prevent the noise. This was soon stopped by the ward manager on
infection control grounds. It is unknown if the problem was rectified.
12.4. Human behaviour
Human behaviour and attitudes are inherently difficult to change in the long term. Studies have shown
that short term noise level improvements can be gained if individuals are made aware of the impact of
their actions in relation to noise. However, this is difficult to implement successfully for any length of
time without a great deal of support from ward management to ensure all policies are strictly adhered
to.
There are many aspects of behaviour cited by both staff and patients in the subjective responses to
the noise environment. Noise level measurements also captured certain activities causing high levels
of noise. Cleaning and the changing of rubbish bins are very necessary activities, but ones that a
number of patients felt could be carried out more quietly. Noise level measurements also found this to
be the case. Loud staff telephone conversations were also mentioned, especially when they were of a
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personal nature and on a mobile phone. Domestic staff talking loudly or shouting at each other across
the ward was found to be annoying by the patients.
Visiting time was listed by a high percentage of staff as annoying and causing interference to their
work. Patients also found large numbers of visitors round a bed disturbing, and some felt that visiting
hours should be more strictly adhered to. Ward managers had very differing views regarding leniency
around visiting times, with some managers feeling that the more contact patients had with their friends
and family, the better. This is obviously a very subjective area, but it is important that visitors are
respectful of other patients on the ward and should also be aware of staff and the duties that they
must perform. If visitors are being loud and impolite it is surely up to the senior members of staff to
control the situation and let it be known that their behaviour is unacceptable and will not be tolerated.
Noise levels in single rooms were often found to be higher and less consistent than those measured
in multi-bed bays. In some instances this was due to the behaviour of those visiting the patients. High
noise levels due to conversation were often captured for long periods of time, with visitors staying on
for an hour or more after the end of designated visiting hours. On occasions staff appeared to turn a
blind eye as the doors to the rooms could be closed and so this would not cause a disturbance to the
other patients on the ward. Of course all patients are recovering and need their rest, and so could
these longer, louder visiting times be potentially detrimental to the patient’s recovery?
Patients crying out in confusion or pain were found to be annoying and disturbing by other patients,
particularly on the medical wards, where there are a higher percentage of elderly patients being cared
for. Patients suffering from confusion or dementia can often be very vocal and it can be both
distressing and disturbing to the other patients in the bay. This is a particularly difficult area to control,
short of segregating these patients, which is not practical in a medical ward running at nearly 100%
occupancy at all times.
Every patient on the study wards was provided with entertainment in the form of a telephone, TV and
radio console, often provided by ‘Patientline’. In most cases patients were provided with headphones
to watch TV or listen to the radio without causing disturbance to others. However, ward managers
admitted that the use of these headphones was not always enforced, resulting in many patients listing
TV / radio use as annoying and disturbing. Perhaps if staff were more aware of the level of annoyance
/ disturbance this causes others, they would be more inclined to enforce headphone use.
Questionnaire responses indicated that on some of the study wards mobile phone use caused
annoyance and disturbance to patients. The use of mobile phones in hospital wards is a contentious
issue with each hospital having their own discretionary policy. The policy at Bedford Hospital, for
example, prohibits the use of mobile phones on the wards, suggesting calls are made in the lobby
areas directly outside the ward. Questionnaire responses from one of the study wards at this hospital
indicated that this policy was not being enforced. Ward managers themselves also have their own
opinions on the use of mobile phones. One of the study ward managers felt so passionately that the
telephone charges incurred as a result of the ‘Patientline’ system were unacceptable, that she allowed
patients to use their mobile phones on the ward.
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12.5. World Health Organisation guidelines
As discussed in Chapter 2, the most recent edition of the World Health Organisation (WHO)
Guidelines for Community Noise was published in 1999 (Berglund et al, 1999). In relation to noise in
hospitals, the guidelines state that ‘the critical effects of noise are on sleep disturbance, annoyance
and the communication interface, including interference with warning signals’. A summary of the
guidelines is shown in Table 12.1.
Table 12.1 – World Health Organisation guidelines for hospital wards and treatment rooms
Specific Environment Critical Health Effects
LAeq (dB) Time Base (Hours) LAmax (dB)
Hospital, ward rooms, indoors
Sleep disturbance 30 Night time (8 hours) 40
Hospital, ward rooms, indoors
Sleep disturbance 30 Day time and evenings (16 hours)
-
Hospital, treatment rooms, indoors
Interference with rest and recovery
As low as possible
The LAeq value stipulated by the guidelines for both day and night time on a ward is 30 dB LAeq.
Interestingly, no noise levels measured in the study wards were found to comply with these levels,
which is in accordance with the findings by Busch-Vishinac et al in 2005. In their comprehensive study
the authors compiled data from all comparable studies post 1960 which listed LAeq noise
measurement values. Not one single study showed a hospital which complied with the WHO
guidelines for hospital noise. This raises the question of the validity of these guidelines.
The WHO guidelines also stipulate a time base in terms of day and night, with day time beginning at
07.00 and ending at 23.00. Noise levels collected in each study ward suggest that this division is not
realistic for hospital wards, with ward activity generally beginning earlier than 07.00 and decreasing
before 23.00. It was also noted that noise levels were generally found to diminish after the evening
meal had been served at around 18.30, suggesting that an ‘evening’ period may also be applicable
and more realistically reflect activity levels on the wards.
In Chapter 6, the fact that the noise levels decreased earlier during the evening was assumed to be
because this was a children’s ward. However, further analysis of adult wards suggests that this is the
case for all wards.
12.6. Acoustic parameters
As discussed in Section 11.2.3, noise measurements have been presented throughout this study as
average day and night LAeq levels for each bay, with average hourly noise levels (LAeq,1hr) plotted over
24 hour intervals. Levels presented in these ways do provide a general indication of the daily patterns
of noise and the overall levels measured in each bay, but are generally found to be very similar with
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relatively small amounts of variation. Busch-Vishniac et al (2005) also encountered this lack of
variation, which was surprising given that their data was gathered from widely differing sources.
To illustrate the fluctuating nature of the measured noise, and help build up a more detailed picture of
its content, high level noise events (over 70 dB LAmax) have been investigated throughout this study
and these are reported in some detail in Chapters 7 and 9. The use of the trigger files captured has
provided a means of identification of all high level sources of noise, and it is felt that by looking at the
types and also the numbers of high level noise sources over a measurement interval, this study has
gone some way in providing data to describe the realities of the noise climate on the wards.
12.7. Conclusions
The discussion in this chapter has shown that it is important to consider noise control at the design
stage of a hospital building. However, much of the impact of noise is related to the patient group, the
activity and behaviour of staff and patients, and the supporting equipment.
The next chapter presents the overall conclusions to the study and recommendations for further work.
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13. Conclusions
13.1. Introduction
This study has investigated, through objective and subjective surveys, the noise climate and acoustic
design within general inpatient facilities in the UK, and their influence on the acoustic comfort of
patients and staff. Noise and acoustic surveys have been carried out in six inpatient wards in three
major UK hospitals, with corresponding questionnaire surveys of staff and patients.
It has been shown that high levels of noise are not confined to ICU and operating theatres, but are
found to be significant throughout inpatient wards in UK hospitals.
Overall conclusions from the study are presented below, together with recommendations arising from
the study and suggestions for further work.
13.2. Overall conclusions
13.2.1. Building design
The study has highlighted the need to understand the way the building will be used when occupied
when specifying the acoustic design of a hospital building. Without due consideration expense may be
incurred in relation to the installation of acoustic doors and sound attenuating material, when in reality
they may be of no actual benefit. This has been illustrated by the ‘open door nursing’ policy in use in
UK hospitals, where staff are trained to nurse with doors open at all times for observational purposes.
Careful thought must be also given to the ward layout to ensure that there are no direct sound paths
from potentially noisy areas, such as kitchens, healthcare utilities and nurse stations, to patient
accommodation.
It has been shown that lower reverberation times result in lower noise levels. This stresses the need
for sufficient acoustic absorbency on the wards in order to reduce noise, which can be attained by
using good quality acoustic ceiling tiles. A new range of ceiling tiles that withstand stronger cleaning
agents are now generally available for use in hospitals following infection control concerns. This
proactive response by the manufacturers has ensured that in future the acoustic design of the wards
need not be compromised by Control of Infection policies.
The study found some evidence to suggest that there was a slight downward trend in noise levels and
building age. Measured day time noise levels were found to decrease between buildings built in the
1970’s, 1980’s and in the last ten years suggesting the more recent use of acoustic design guidelines
may be having some effect.
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13.2.2. Patient accommodation
The study has found that contrary to general assumption, noise levels are unrelated to bay size and
numbers of beds, with some of the highest noise levels measured in single bed rooms. Furthermore,
patients in single rooms were found to be more annoyed by day time noise and more disturbed by
night time noise than those in multi-bed bays.
Conversational privacy was rated most poorly by patients in 3-bed bays, with improvements found in
four to twelve bed bays. 100% of patients in single rooms were found to be satisfied with speech
privacy.
Measured noise levels in a medical and surgical ward at the same hospital were found to be similar,
but the sources of the noise and the staff and patient perceptions differed.
13.2.3. Staff and patient perceptions
Ratings of noise annoyance and interference by staff at the main study hospitals were generally low;
mostly in the ‘slightly’ to ‘moderately’ range. However, there were noticeable differences found with
longer term staff (> 5 years service) rating noise interference more highly than noise annoyance, and
more highly than staff who had worked on the ward or in the hospital for a shorter time.
Analysis of the patient questionnaire responses from the main study sites indicated a shift in the
attitude amongst longer term patients (> 3 weeks stay) to the noise climate, with increased sensitivity
during the day but decreased sensitivity at night. This may suggest a certain amount of
acclimatisation to night time noise. It was also found that patients in the 41-50 age group were more
highly annoyed and disturbed by noise than any other age group.
13.2.4. Ward equipment
The study shows that the cacophony of alarms and tones emitted by the electronic equipment in use
on the ward are a major source of noise, with the nurse call, internal telephone, ward doorbell and
medical equipment continually cited as causes of annoyance throughout the study. Ward staff found
much of this equipment to be either inflexible, faulty, over complicated or not fit for purpose. Training
in the use of electronic equipment appeared to be lacking.
Much of the noise attributed to ward furniture could be rectified by simple noise control measures,
such as fitting rubber feet or wheels to furniture; fitting and maintaining quiet door closers; a common
sense approach to the positioning of rubbish bins; and the replacement of ring binders.
Simple ward maintenance was found to be an issue, with no clear fault logging process available to
sort out problems such as an ineffectual door closer.
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13.2.5. Human behaviour
Although human behaviour and attitudes are inherently difficult to change in the long term, it is felt
that if staff, patients and visitors were made aware of the effects of their actions on the noise climate,
they might think more carefully in the future. Thus, education of users of a hospital, accompanied by
support and further enforcement by senior management may be needed to change the current culture
to a culture of ‘quiet’.
13.2.6. Guidelines
Most of the current acoustic design guidelines were not found to be applicable to an occupied
building; only the WHO guidelines for healthcare were concerned with noise levels in an occupied
ward. However, these guidelines have been shown to be unrealistic and a review is needed of both
noise levels and day and night divisions.
13.3. Recommendations
The study has highlighted the need for adequate consultation with the building’s users before the
acoustic design criteria is specified for a new or existing building. This will allow a realistic set of
acoustic requirements to be established that will positively support the building’s users and ensure
that money is not spent on un-necessary acoustic treatment.
Post occupancy surveys should be carried out some months after a new hospital building is first
commissioned to ensure that the building is functioning as it was designed. Staff should be involved in
this process, providing feedback regarding any problems they may have in terms of their environment
and the ward systems. Feedback mechanisms should be put in place that encourage problems to be
reported, no matter how small.
Due to a lack of funding for new hospital buildings, refurbishment of the existing hospital building
stock will be carried out over the next decade more extensively than ever. To ensure that the limited
funding available targets the correct areas, it is important that adequate consideration is given to the
staff and patient experience. Some of the differences in opinion identified during the study highlight
the need to focus on areas of the greatest impact. For example, fitting expensive double glazed
windows to an entire building may not have as much effect as changing the suspended ceilings, or
making changes to some of the more problematic ward systems.
Ongoing ward maintenance needs a proper reporting structure to be put in place. If this does not
exist, busy staff will simply ‘put up with’ issues that cause them annoyance and interference,
assuming that nothing will be done. Regular reviews either by the estates teams or by ward
management, who subsequent report to the estates teams, should be carried out.
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Adequate training on the use of ward systems should be provided for new and existing staff and this
should be an ongoing process.
It is imperative that manufacturers take the noise impact into consideration when developing any type
of new system or piece of equipment to be used on a hospital ward. Collaboration with staff is strongly
recommended to ensure that their requirements are incorporated. Simplicity of use should also be a
priority.
It is felt that with properly implemented and maintained systems and equipment; an effective feedback
system; a proactive approach to the management of noise issues by senior staff; and a common
sense approach to noise control, many of the issues highlighted by the study could be improved and
even eradicated completely.
13.4. Further work
The following areas would benefit from further work:
� Raising the awareness of hospital ward equipment and systems manufacturers as to the
potential impact of their equipment on hospital noise, and on staff and patients.
� Design of medical equipment alarms to ensure that tones are only emitted when necessary,
and that the alarms themselves are suitable for the event type.
� Development of more realistic guidelines for noise levels in occupied wards, including a more
suitable day, evening and night division.
� Investigation of the feasibility and the trialling of replacement technology which incorporates
wireless and silent technology that could replace existing systems such as the internal
telephone, doorbell and nurse call.
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Appendix A
1. Study publicity poster
2. Staff information sheet
3. Staff questionnaire
4. Patient questionnaire
5. Response from the National Research Ethics Service (NRES)
6. Ethical approval received from London South Bank University
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Is it too Is it too Is it too Is it too
noisy?noisy?noisy?noisy?
Research is currently being carried out by the Estates Team here at XXXX
Hospital together with London South Bank University. The purpose of this
research is to understand the impact of noise on patients and staff in the wards.
We are also keen to find out whether the design and materials used in our
buildings help to make the buildings less or more noisy for everyone who uses
them.
Research into the Acoustic Environment
The first part of the research will involve taking some
sound level measurements. This will help us to build
up an understanding about the noise levels and
sources of high level noise in the ward environments.
To enable these measurements to be made, a portable
sound level meter will be used. This meter measures
sound levels in Decibels. The meter is small and
unobtrusive and please be assured that it will be
sterilised prior to use.
The second part of the research is about understanding your feelings about
noise - the patients and staff who spend time in the ward environments. A short
questionnaire of no more than 10 minutes in length will allow us to build up an
understanding of how the building is viewed in terms of noise. This will be on a
completely voluntary basis and all information collected will be anonymous.
Your involvement will be greatly appreciated to help positively influence the
environment for the future.
Sound Level Meter
Research Steps
For further information or to register your interest in participating in the study
please contact XXXX in the Estates Team. Alternatively email Nicky Shiers at
1.
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Research into the Acoustic Environment
You are being invited to take part in a research study. Before you decide it is
important for you to understand why the research is being carried out and what it will
involve. Please take time to read the following information carefully. Talk to others
about the study if you wish.
Please ask us if there is anything that is not clear or if you would like more
information. Take time to decide whether or not you wish to take part.
The aim of this research is to investigate the impact of noise on the staff such as
yourself, in the clinical environment in which you work. The results will enable us to
understand whether the design and the materials used in the hospital buildings have
a positive or negative impact on your acoustic comfort.
This study is being completed as part of a PhD at London South Bank University and
is being run in conjunction with the Estates Team here at XXXX Hospital.
The initial part of the study will involve the researcher making some sound level
measurements. This will help to build up an appreciation of the actual noise levels
and sources of high level noise in the ward environments.
The second part of the research will involve the completion of a questionnaire to
explore your perceptions of the ward environment in relation to noise. The
questionnaire should take between 5 and 10 minutes to complete.
Of course, it is up to you to decide whether or not to take part. If you do so, you will
be given this information sheet to keep. You are still free to withdraw at any time and
without giving a reason.
No personal information will be asked of you in the questionnaire and all information
you do provide will be handled in a confidential manner and stored in a locked filing
cabinet and on a password protected computer in an environment locked when not
occupied. Only the researcher and supervisor will have direct access to the
information. Any reference to you will be coded. This information will be held until the
end 2012.
If you have a concern about any aspect of this study, you should ask to speak with
the researcher who will do their best to answer your questions. The contact details of
the researcher are shown at the end of this sheet. If you would like any further
Is it too Is it too Is it too Is it too
noisy?noisy?noisy?noisy?
2.
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259
information regarding this study or have any complaints about the way you have
been dealt with during the study or other concerns you can contact: Rosemary
Glanville, Head of the Medical Architecture Research Unit on 0207 815 8329, who is
the Academic Supervisor for this study. Finally, if you remain unhappy and wish to
complain formally, you can do this through the University’s Complaints Procedure.
Details can be obtained from the university website: http://www.lsbu.ac.uk/research
Researcher’s Contact Details:
Mrs Nicola Shiers
Medical Architecture Research Unit
Faculty of Engineering, Science and the Built Environment
London South Bank University
103 Borough Road
London
SE1 0AA
T: 0207 815 8395 E: [email protected]
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Research into the Acoustic Environment
This questionnaire forms part of a study being carried out by the Estates and
Facilities Team here at XXXX Hospital together with London South Bank
University. The purpose of research is to understand the impact of noise on staff
and patients in the wards.
The questionnaire should take between 5 and 10 minutes to complete and is of
course completely voluntary. By completing this questionnaire you are
consenting to take part in this study. The responses which you give will be
completely anonymous.
The questions concern how annoyed you are by noise and how much noise
interferes with your ability to do your work.
About You
1. Are you?
� Male � Female
2. What age are you?
� Less than 20 � 20-30 years � 31-40 years
� 41-50 years � 51-60 years � 60+ years
3. What staff grade are you? ………………
4. How long have you worked on this ward?
� Less than 1 year � 1-2 years � 2-3 years
� 3-4 years � 4-5 years � 5+ years
5. How long have you worked at this hospital?
� Less than 1 year � 1-2 years � 2-3 years
� 3-4 years � 4-5 years � 5+ years
3. SSSSoundoundoundound IN IN IN IN
YOURYOURYOURYOUR
HOSPITALHOSPITALHOSPITALHOSPITAL
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About Your Environment
1. Do you ever feel annoyed by noise while you are at work?
� Not at all � Slightly � Moderately � Very much � Extremely
Please indicate on a scale from 0 to 4 how much you are annoyed by each of
the following noises (0 indicating ‘not at all’ and 4 indicating ‘a great deal’)
0 1 2 3 4
External noise (traffic, aircraft etc) � � � � �
Doors banging � � � � �
Internal telephones ringing � � � � �
Staff talking on the telephone � � � � �
Nurse call � � � � �
Door bell � � � � �
Footsteps � � � � �
Medical equipment alarms � � � � �
People talking � � � � �
Cleaning � � � � �
Rubbish Bins � � � � �
Trolleys � � � � �
Meal times � � � � �
Television / radio � � � � �
Mobile phones ringing � � � � �
People talking on mobile phones � � � � �
Visiting time � � � � �
Other (please specify and rate)
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
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2. Overall, how much do you feel that noise interferes with your ability to do
your work?
� Not at all � Slightly � Moderately � Very much � Extremely
Please indicate on a scale from 0 to 4 how much each of the following noises
interferes with your ability to do your work (0 indicating ‘not at all’ and 4
indicating ‘a great deal’).
0 1 2 3 4
External noise (traffic, aircraft etc) � � � � �
Doors banging � � � � �
Internal telephones ringing � � � � �
Staff talking on the telephone � � � � �
Nurse call � � � � �
Door bell � � � � �
Footsteps � � � � �
Medical equipment alarms � � � � �
General conversation � � � � �
Cleaning � � � � �
Rubbish Bins � � � � �
Trolleys � � � � �
Meal times � � � � �
Television / radio � � � � �
Mobile phones ringing � � � � �
People talking on mobile phones � � � � �
Visiting time � � � � �
Other (please specify and rate)
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
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3. It is important for you to be able to hear some sounds in order for you to
carry out your job effectively.
Please rate the importance of each of the following sounds on a scale from 0
to 4, where 0 indicates ‘not at all important’ and 4 ‘extremely important’.
0 1 2 3 4
Nurse call � � � � �
Conversations with colleagues � � � � �
Conversations with patients � � � � �
Equipment alarms � � � � �
Patients calling out � � � � �
Patient activity � � � � �
Other (please specify and rate)
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
4. Sometimes high levels of background noise can make it difficult to hear
important sounds. Please indicate on a scale from 0 to 4 how difficult it is to
hear in the following locations:
I can It is very
always difficult
hear to hear
0 1 2 3 4
Nursing Station � � � � �
Hallway � � � � �
4 bed bay � � � � �
Single patient room � � � � �
Treatment Room � � � � �
If you have any further comments regarding noise, please write them
in the space below.
………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………
THANK YOU FOR TAKING THE TIME TO
COMPLETE THE QUESTIONNAIRE
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Research into the Acoustic Environment
This questionnaire forms part of a study being carried out by the Estates and Facilities
Team here at XXXX Hospital together with London South Bank University. The purpose of
research is to understand the impact of noise on patients and staff in the wards. We are
also keen to find out whether the design and materials used in our buildings help to
make the buildings less or more noisy for everyone who uses them.
The questionnaire should take between 5 and 10 minutes to complete and is of course
completely voluntary. By completing this questionnaire you are consenting to take part
in this study. The responses which you give will be completely anonymous.
About you
1. Are you?
� Male
� Female
2. What age are you?
� Less than 20
� 20-30 years
� 31-40 years
� 41-50 years
� 51-60 years � 60+ years
3. How many days have you been at hospital this time? (Please enter number in boxes
below)
� days Bed Number�
SSSSoundoundoundound IN IN IN IN
YOURYOURYOURYOUR
HOSPITALHOSPITALHOSPITALHOSPITAL
4.
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About Your Environment
1. During the daytime in this ward, would you say it is:
� Very quiet � Quiet � A little noisy � Very Noisy � Extremely Noisy
2. Are you ever annoyed by noise during the daytime?
� YES � NO
If you answered ‘YES’, please indicate on a scale from 0 to 4 how much you are
annoyed by each of the following noises (0 indicating ‘not at all’ and 4 indicating ‘a
great deal’)
0 1 2 3 4
External noise (traffic, aircraft etc) � � � � �
Doors banging � � � � �
Internal telephones ringing � � � � �
Staff talking on the telephone � � � � �
Nurse call � � � � �
Door bell � � � � �
Footsteps � � � � �
Medical equipment alarms � � � � �
People talking � � � � �
Cleaning � � � � �
Rubbish Bins � � � � �
Trolleys � � � � �
Visiting time � � � � �
Meal times � � � � �
Television / radio � � � � �
Mobile phones ringing � � � � �
People talking on mobile phones � � � � �
Other patients crying out � � � � �
Other (please specify and rate)
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
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3. After lights are turned out and you are trying to sleep, would you say the ward is:
� Very quiet � Quiet � A little noisy � Very Noisy � Extremely Noisy � Don’t know
4. Are you ever disturbed by noise after lights out?
� YES � NO
If you answered ‘YES’, please indicate on a scale from 0 to 4 how much you are
disturbed by each of the following noises (0 indicating ‘not at all’ and 4 indicating ‘a
great deal’)
0 1 2 3 4
External noise (traffic, aircraft etc) � � � � �
Doors banging � � � � �
Internal telephones ringing � � � � �
Staff talking on the telephone � � � � �
Nurse call � � � � �
Door bell � � � � �
Footsteps � � � � �
Medical equipment alarms � � � � �
People talking � � � � �
Rubbish bins � � � � �
Trolleys � � � � �
Television / radio � � � � �
Mobile phones ringing � � � � �
People talking on mobile phones � � � � �
Other patients crying out � � � � �
Other (please specify and rate)
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
…………………………………………………….. � � � � �
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5. Are there any noises that you actually finding comforting?
Please specify ………………………………………………………………..
……………………………………………..................
6. When doctors and nurses talk to you, can you always hear them clearly?
� I can always clearly hear what people say
� Occasionally high levels of noise make it hard to hear
� Often high levels of noise make it hard to hear
7. Do you consider that it is possible to hold a private conversation here?
� YES � NO
8. If you answered ‘yes’ to question 7 and wanted to hold a private conversation, would
you:
� Use your normal voice
� Lower your voice
� Take some other precautionary measure
If so please specify ……………………………………………………
9. Do you ever feel that there is too little sound in here?
� YES � NO
10. Do you suffer from any hearing impairment that you know of?
� YES � NO
If you have any further comments regarding noise, please write them in the space
below.
………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………
THANK YOU FOR TAKING THE TIME TO
COMPLETE THE QUESTIONNAIRE
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5. Copy of email response from the National Research
Ethics Service for the NHS (NRES)
RE: Research Enquiry
NRES Queries Line [[email protected]]
To: Shiers, Nicola
Cc:
Your query was reviewed by our Queries Line Advisers.
We would classify this as a type of service evaluation and it does not
require REC review.
Regards
Queries Line
National Research Ethics Service
National Patient Safety Agency
4-8 Maple Street
London
W1T 5HD
Website: www.nres.npsa.nhs.uk
Email: [email protected]
Ref: 04 /31
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6. Ethical approval received from London South Bank
University (scan of relevant signatures)
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14. Appendix B
1. Great Ormond Street Hospital parent / patient questionnaire comments
2. Bedford Hospital staff questionnaire comments
3. Bedford Hospital patient questionnaire comments
4. Addenbrooke’s Hospital staff questionnaire comments
5. Addenbrooke’s Hospital patient questionnaire comments
6. Comforting sounds
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1. Great Ormond Street Hospital parent / patient questionnaire comments
Comments made are listed below:
� ‘General level is ok but sometimes conflicting TV/radio can be annoying. Would free
earphones be appropriate?’
� ‘Noise of a working area is never a problem. Sometimes silence is nice. Children
communicating and other carers is very enjoyable and helpful.’
� ‘Headphones for children after lights out?’
� ‘Some TV’s can be very loud.’
� ‘Would be helpful if the entrance door to the ward could be closed at night time. This would
eliminate a lot of the noise from the corridor and the other wards.’
� ‘Some noise depends on where your child’s bed is situated, so because we were away
from the nurse’s station the phone and conversation did not affect us, but the doorbell was
quite noisy.
� ‘Patients have TV’s very loud and have them on during the night. Each patient should be
issued with ear phones so that TV/radio noise does not disturb others in the wards.’
� ‘The drilling has been a mild nuisance and the fire alarm going off for 35 minutes at
5.20am made sleep impossible. The utility room opposite our room is used frequently
during the day and night and the door makes a loud bang every time which kept us both
awake. Quiet closers on the doors would help.’
� ‘It is quite difficult to determine what is too noisy as it is so dependent on what situation
your child is in at the time.’
� ‘We have spent the last three days with our daughter recovering from spinal surgery. We
are in a 4-bed bay with two other patients and next to a child who has special needs and
benefits from loud music. She is also very vocal and both we and our daughter found this
intrusive when she was feeling very unwell. This was not the fault of the other family, but
was not conducive to our well being.
Suggestions:
� Provide wireless headphone (perhaps two sets per bed to allow a visitor
to listen as well as the patient).
� Limit the volume on each TV.
� Put speakers closer to the patient – when 3 ceiling mounted TV’s are set
to different channels it is a real cacophony of sound.
To illustrate how difficult it was at times, our daughter was lying with her fingers in her
ears’.
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2. Bedford Hospital staff questionnaire comments
� ‘I wish the curtains between patient’s beds could be sound proofed so you could have a
confidential / private conversation without the rest of the bay hearing’.
� ‘I am partially deaf so find it difficult to hear when there is a lot of background noise. I often
have to ask other staff members to repeat themselves or to clarify what they have said’.
� ‘I don’t think there is too much of a problem on the ward regarding noise’.
� ‘Did you know? There are crickets living in the elevators at Bedford hospital, chirping at
night’.
3. Bedford Hospital patient questionnaire comments
Medical ward patients:
� ‘It appears that if a patient is noisy and aggressive their attentions are responded to
quicker, that is bed pan, bathing etc. Quiet patients are often ignored or completely
forgotten as the staff are over pushed and failing in essential human contact in most of
their functions. Perhaps quiet areas could be assigned and less aggressive patients
attended to quicker and more efficiently rather than excluded by aggressive nutters who
dominate the ward by vocal, noisy and constant requests for un-needed “help” ’.
� ‘We only had one night of noise’ – it should be noted that this was over the course of an 8
day hospital stay.
� ‘Kitchen door left open after meal times so loud banging / washing up can be heard.
Cleaning staff shouting at each other from one end of the room to kitchen.’
� ‘Staff making personal calls on mobiles. I don’t really want to know whom they met in the
pub last night and whether they will go out for a curry or Chinese.’
� ‘I’m very grateful for the kindness of all the staff – from kitchen staff to doctors.’
� ‘Only sometimes noisy when a large family get around the bed, for example 6 or 7 people.’
� ‘Angry patients mouthing at everyone and not taking full responsibility for their own
misgivings.’
� ‘I accept that there is bound to be a certain level of noise day or night, and understand the
difficulties that staff have to do their job and at the same time try not to disturb the
patients.’
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Surgical ward patients
� ‘When the background noise is low as at night, individual noises are more disturbing’
� ‘The bay is very close to the entrance door and the reception desk. There is continual
traffic past bay 1 to the other bays. Perhaps the desk should be located before the
entrance door.
� ‘I think staff can be very inconsiderate during the night – laughing out loud – slamming
doors – to us who are not necessarily ‘worn out’ they sound like clanging cymbals. It is not
easy to sleep when it is very light.’
� ‘As a poor normal light sleeper I find the lights left on during the night really hard. Have to
use alarm to get light switched off.’
� ‘The ward is the quietest ward I have been on.’
� ‘Wherever you are these days you expect to hear a certain amount of noise such as traffic,
and you take it for granted. One wouldn’t want to live in a totally silent world, missing bird
song and human voices.’
� ‘Thank you.’
� ‘The buzzer [nurse call] in the nurse station is a little disturbing.’ (This patient was in the 4-
bed bay directly opposite)’.
� ‘Visiting – very unclear times: are they the same at weekends?’ & ‘external noise very bad’
� ‘I found the noise at night more of a problem than my previous visit – my bed is the closest
to the nurse station so I get all the buzzer noises [nurse call] / phone calls etc and lots of
walking up and down. Some shoes squeak more than others!’
� ‘May I suggest that trolleys are fitted with pneumatic tyres – would cut out a lot of clatter. I
know cleaning has to be done and appreciate the cleanliness, but could it be done a little
quieter? Please thank the staff for all their help, assistance and very friendly attitude.’
� ‘Doors are ill-fitting and a constant annoyance.’
� Other sources of noise annoyance mentioned cited by one patient who was in a single
room – ‘outside building noises; water pipes / pumping sounds; truck outside moving
bins/rubbish – siren sounds when reversing; continual humming from electrical machine
outside; police/ambulance sirens throughout the day; obviously staff not shown how to
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move rubbish bins / bags quietly. The doors are the main problem banging, and staff agree
too.’
� ‘I accepted noise as part and parcel of ward life’.
� Patient staying in a single room and listed squeaky hinges on doors as annoying.
� Patient is disturbed by mobile phones ringing during the night and suggests that they
should be put on silent.
4. Addenbrooke’s Hospital staff questionnaire comments
� ‘Often construction noise can be heard on the ward. Obviously inevitable with planned
expansion, but this disrupts patient’s rest and peace and quiet’ (D8)
� ‘What may make noise felt more is the space (lack of) and narrowness of the ward’ (D8)
� ‘When visiting hours were restricted and all visitors came at a certain time it became quite
noisy within bays’ (D8)
� ‘The most annoying noise I can think of is relatives / others pushing the doorbell; then if
you don’t answer straight away they ring again and again. It is a noise that is too loud and
unnecessary’ (M4)
� ‘Noise and excessive noise is everywhere in the ward environment – none more irritating
than the specific sounds use to catch attention, especially those of the telephone – which
not only catches attention but causes some discomfort and stress when other tasks take
over. If these sounds were different – soothing but alertive and not repetitive, this may help
reduce stress’ (M4)
� ‘There is no emergency alarm sound in the staff room, so if you’re in there you can’t hear
an emergency call’ (N3)
5. Addenbrooke’s Hospital patient questionnaire comments
� ‘I’m glad research into this is being done as I greatly believe in the visual and acoustic
environment has great impact on one’s recovery.’ (D8)
� ‘Noises at night often make it hard to sleep.’ (D8)
� ‘Women in high heels walking in the corridors.’(D8)
� ‘I probably make most of it, so I apologise to other patients and the staff. Also I am not that
bothered about other patients crying out now, you get used to it.’ (D8)
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� ‘A set of earplugs should be issued to each person.’ (D8)
� ‘One prevalent cause of noise is dictated by fashion and could not easily be changed.
Today’s version of clear, open, optimistic and especially young person in hospital
employment is uninhibited and class-free. This is fine in many ways, but does leave a
range of opportunities for serious and comforting discourse socially unrepresented and
indeed of quite unfamiliar character.’ (D8)
� ‘Pleased with treatment from staff. Concerned – as a younger person should there be a
separate bay for the dementia patients – as fairly distressing at times when crying out.’
(D8)
� ‘The thumping of the external building work could not only be heard, but also felt coming
up through the floor and made conversations with visitors very difficult.’ (D8)
� ‘When a patient is continually shouting and crying out in pain then I would suggest trying
to isolate them from other patients.’ (D8)
� ‘Noise levels at night are extremely high and have kept me awake for 2 nights.’ (N3)
� ‘I feel that all staff respect patient’s privacy and deal with any problems that arise.
Sometimes visiting hours can be a bit noisy but to be expected, unless doing it to annoy
others’. (N3)
� ‘Patients talking on mobile phones and land lines late at night. Patients watching TV via
their laptops. Staff unwilling and unable to ask patients to stop using their mobiles and be
quiet. Foul language while using phones and in general conversation between visitors and
patients. Sleep is very important for recovery and there should be a set time for lights out
etc. Visiting times should be enforced!’ (N3)
� ‘I have a hearing problem that hearing aids can sometimes make surrounding noise very
disturbing, therefore I am not good at judging noise levels generally.’ (N3)
� ‘Some of the staff wearing heels and the noise of the doorbell. No one answering the
phone so it is always going off.’ (M4)
� ‘The turning on of TV’s / radios when on speaker is very annoying and inconsiderate,
especially first thing in the morning.’ (M4)
� ‘You have to give and take…. (M4)
� Maybe a hospital volunteer or WI member could be on call to answer the phone.
� When people are sick you are going to get noise.
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276
� Foreign accents are especially difficult for the elderly.
6. Comforting sounds
Bedford Hospital
� Traffic
� Life going on outside
� Nurse activity
� Nurses talking quietly
� Knowing someone is near
� Knowing staff are there
� Tea trolley (2 responses)
� Music on the radio (3 responses)
� Nurses' voices
� People's voices
� Silence
� Specific person's ring tone
Addenbrooke’s Hospital
� Knowing staff are there (4 responses)
� Floor cleaner (sent patient to sleep)
� Birds outside
� Listening to music /radio (3 responses)
� Noise of trains on nearby railway (2 responses)
� Singing, laughter, good humour
� Nurses comforting patients (2 responses)
� Tea trolley and nurse’s pleasant good mornings (2 responses)
� Voices of wife and daughters
� Droning noises – nebulizers, Hoovers etc
� Aircraft
Acoustic Design for Inpatient Facilities in Hospitals Appendices
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Appendix C
Corner corrections
Throughout the study, care was taken in the positioning of the microphone and associated equipment
was so as to minimise its impact on staff duties and patient care. There were also constraints
regarding of the length of cable between the microphone and the environmental case housing the
sound level meter (5m). In most instances these constraints meant that the microphone was situated
close to the edge of room, often in the corner, with the microphone suspended from the ceiling on a
300mm bracket.
Due consideration was given to the possible increase in sound pressure that may occur as a result of
wall or corner reflections. A number of tests were carried out to investigate this, with simultaneous
LAeq measurements made both in the centre of the room and at the main equipment location, that is
close to the corner or wall of the room. The results are shown in the table below. It can be seen that
the average difference between the measured levels was low (0.61 dB), and thus it was felt that no
correction to measured levels was required.
Position Date Start time Elapsed Time (m:ss) End Time LAeq (dB) Difference
Nurse station, D8 - in front of nurse station 58.5
Nurse station, D8 - microphone suspended in corner 56.9
12-bed bay, D8 - centre of the ward 59.0
12- bed bay, D8 - microphone suspended close to wall 59.1
4-bed bay, D8 - centre of the ward 63.5
4-bed bay, D8 - microphone suspended in corner of ward 63.1
6-bed bay, surgical ward, Bedford - centre of ward 48.0
6-bed bay, surgical ward, Bedford - microphone suspended in corner 46.6
Nurse station, surgical ward, Bedford - in front of nurse station 56.8
Nurse station, surgical ward, Bedford - microphone suspended above nurse station 56.7
4-bed bay 1, surgical ward, Bedford - centre of the ward 47.8
4-bed bay 1, surgical ward, Bedford - microphone suspended in corner 46.0
7-bed bay, D8 - centre of the ward 62.0
7-bed bay, D8 - microphone suspended in front of wall 61.4
Single room 3, surgical ward, Bedford - microphone in centre of room by bed end 50.3
Single room, surgical ward, Bedford - microphone suspended over the window 50.5
Single room 1, surgical ward, Bedford - microphone in centre of room by bed end 53.5
Single room 1, surgical ward, Bedford - microphone on mini tripod on light over mirror 53.2
4-bed bay 2, surgical ward, Bedford - centre of the ward 44.0
4-bed bay 2, surgical ward, Bedford - microphone suspended in corner 44.2
3-bed bay, D8 - centre of the ward 60.7
3-bed bay, D8 - microphone suspended in centre of ward close to wall 59.7
Average difference = 0.61 dB
-0.2
13.13.053.0213.10.0324.06.10
21.07.10 11.51.55 3.02 11.54.57
21.07.10 15.36.04 1.18 15.37.22
14.07.10 11.34.10 3.02 11.37.12
01.07.10 15.23.39 3.01 15.26.40
07.07.10 12.28.12 3.01 12.31.13
24.06.10 13.38.10 5.24 13.43.34
01.07.10 11.06.22 3.01 11.09.23
23.06.10 17.00.46 2.59 17.03.45
1.0
02.06.10 12.34.56 3.04 12.38.00
9.6.10 10.12.56 3.07 10.15.03
1.8
0.6
-0.2
0.3
1.6
-0.1
0.4
1.4
0.1