ESSEX STUDY Classroom Acoustics: David Canning London Borough
Newham [email protected]
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OVERVIEW Purpose of the Essex study Practical aspects of the
study Principal acoustic findings
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THE QUESTION POSED BY ESSEX CC Purpose of the Study: How should
we refurbish mainstream classrooms so that they are acceptable
listening environments for hearing impaired children. Supplementary
questions: What is the impact of modifying the physical acoustical
performance on the occupied class engaged in learning? Is there a
measureable acoustic impact? Is there an impact on teaching and
learning? -If there is an impact, then how does this information
contribute to the specification and design of teaching spaces?
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INTRODUCTION
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THREE PRINCIPLES: Experimental Approach We chose to design an
approach that would be useful in determining causality
Generalisable Change one variable only Staff and children blind to
condition Analysis of acoustic data will be carried out blind to
the condition Achievable Given all the constraints, time, possible
disruption, cost, equipment and support from the school and
LEA.s
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CLASSROOM SELECTED Typical cellular classrooms, typical of the
majority of school buildings for children 11yrs 16yrs in the
UK:
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PRACTICAL ASPECTS OF THE STUDY Chose one curriculum area:
Mathematics. 4 Identical classrooms Sound treatments that visually
as similar as possible. The school kindly redecorated the rooms.
Ability to change the acoustic performance of all classrooms in the
study over a weekend Staff willing to tolerate and eventually
ignore measurement equipment, observation and repeated
questionnaires over a period of at least 6 months
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CLASSROOM ACOUSTIC TREATMENT Before After Suspended ceiling
added. Acoustics Tiles and Wall Panels. New lights and a coat of
paint to all rooms. Hard walls and ceiling. Windows on two sides.
Carpet bonded to concrete floor. Area = 50sqm
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SELECTION OF ACOUSTIC MATERIALS Acoustic panels absorb sound
energy. The nature of the material used, and the manner in which is
used all have an impact on the absorption characteristics
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SCHEDULE OF ROOM TREATMENTS Experimental Condition British
Association of Teachers of the Deaf (batod) Rt 0.9s mid
frequencies) Pre test (all untreated) Classrooms A,B,C& D Phase
1Classroom AClassroom BClassroom CClassroom D Phase 2Classroom
CClassroom AClassroom BClassroom D Phase 3Classroom BClassroom
CClassroom AClassroom D
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SELECTION OF GROUPS 10 teachers 8 Classes taught exclusively in
one of the rooms 3 of the 4 classrooms were predominantly used by
the same teacher Teacher class combinations 10 teacher and class
combinations were included in the study Groups included grades 7
(11yrs) to 10 (14yrs) Top, middle and bottom ability sets Children
400 children included in the study Including 17 children with
hearing impairment
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OUTCOME MEASURES Room Unoccupie d Physical Acoustics: Rt, EDT,
C 50 etc Functional Acoustics Signal to Noise measurements sound
levels Teacher and Child ratings LIFE UK Hearing performanc e :
Speech discrimination Interviews and observati ons Expert panels
-Occupied Sound Levels, -Signal to noise levels
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PRINCIPAL ACOUSTICS FINDINGS ACOUSTIC TREATMENT AND CLASSROOM
NOISE Very significant changes in occupied sound levels: 17dB from
untreated to highest level of treatment (1.2 s to 0.4s) 9dB
Reduction in Background Noise from current standard to proposed
standard for children with special hearing requirements 0.40.8
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L 90 PLOTTED AGAINST RT (REVERBERATION TIME) EACH OF THE TREE
CLASSROOMS Ultra strict teacher Ultra relaxed teacher 7 Teachers
Control Classroom
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PREDICTOR IMPORTANCE
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65dB EXCEEDENCE LEVEL
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THE SIGNIFICANCE OF ACOUSTIC ABSORBENCY (SHORT REVERBERATION
TIMES) ON FUNCTIONAL SIGNAL TO NOISE LEVELS 0.4
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PUPIL VIEWS
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http://eastafrica.usaid.gov/images/Photo.300.1407.asp x IDEAL
CLASSROOM FOR GROUP WORK
