WRITTEN

BY

ESEKA EHIEMENONYE .C ARC/09 /7376

ESSIEN EKERETE .E ARC/09/7378

SUBMITTED

TO

PROFESSOR OGUNSOTE O.OIN PARTIAL FULFILLMENT OF

ENVIRONMENT CONTROL III

(ACOUSTIC AND NOISE CONTROL)

ARC 507

JULY, 2014.

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TABLE OF CONTENT PAGE

1.0 INTRODUCTION 3

2.0 CLASSROOM ACOUSTICS 4

2.1 transmissions of sound 4

2.11 reverberation time 4

2.12 background noise 4

2.2 CLASSROOM DESIGN FOR GOOD HEARING 7

2.21 Requirements for good hearing in classrooms 7

2.22 Examples of effective classroom design 8

3.0 INDOOR ACOUSTIC STANDARD OF FUTA STAFF SECONDARY

SCHOOL (CASE STUDY) 9

3.1 Site plan 9

3.2 Plan of internal space 10

3.3 Ceiling plan of internal space 11

4.0 PERCEPTION OF THE SPACE 13

4.1 Proposal for improving the indoor acoustic standard of a

classroom 13

5.0 CONCLUSION 14

REFFERENCE 15

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1.0 INTRODUCTION

This paper critically examines the indoor acoustic standard of a classroom by describing its

form, wall and ceiling finish, site plan showing the various sources of noise that affect the

background noise, plans of the internal space showing the furniture arrangement, stating the

materials and finishes used, using the interior shape and spaces to describe how it affects the

audibility of the speech during discussions and also suggesting ways and methods of

improving or enhancing the acoustic standard of the space in question. The acoustics of

internal spaces are very important, often neglected, aspect of most environments. Up to 60%

of indoor activities involve speech between a speaker and an audience, indicating the

importance of environments that support clear communication (Accredited Standards

Committee, S12, Noise, 2002). However, lecture halls that have been constructed in the last

20 to 30 years to better engage students in hands-on activities or discussions have often

resulted in active, noisy environments. Additionally, HVAC systems have created distracting

background noise in classrooms (Nelson, 1999).

Inappropriate levels of background noise, reverberation, and signal-to noise ratios can also

inhibit reading and spelling ability, behaviour, attention, concentration, and academic

performance. Furthermore, children who develop language skills in poor acoustic

environments may develop long-term speech comprehension problems (Smaldino &

Crandell, 1999). Good classroom acoustics are a basic classroom need, not an accessory, to

give all students access to spoken instruction and discussion (Pepi, 1999). However, this

paper focuses its research on the indoor acoustic standards of an average Nigerian school

environment using the federal university of technology akure secondary school as a case

study.

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2.0 CLASSROOM ACOUSTICS

Acoustics in Schools is a tool for architects, interior designers, and other design professionals

who work to improve school environments for all users. It is an introduction to the acoustical

issues commonly confronted on school projects. Acoustic problems persist in classrooms

because of a lack of acoustics education for architects and engineers, the prohibitive expenses

of acoustic refurbishment, and because adult listeners often do not consider the limitations of

children are hearing abilities (Muehleisen, N.D). People are immersed in sound all the time

since a person’s well-being and hearing quality depends on acoustics of a room. This aspect

should be carefully considered in the planning and designing stages. Sound moves through

room in straight lines. To a greater or less extent, object will either reflect or absorb sound

depending on the objects surface properties.

2.1 transmission of sound

Depending on how it is transmitted, basically sound is transmitted through four categories:

Airborne sound

Structure borne sound Footfall sound also called impact sound

Liquid borne sound

We would be focusing our research on air borne sound as it applies and affects the learning

environment.

2.11 Reverberation Time

The overall effect of reflected sound is called reverberation, and the time required for

reflected sound to become inaudible is called reverberation time. Short reverberation times

are good for speech intelligibility.

2.12 Background Noise

Any sound that is generated outside the building, such as playground activity, traffic and

planes can be considered background noise. It generally intrudes in the classroom by way of

the windows. Within the building, an HVAC (heating, ventilation, and air conditioning)

systems and corridor noise can contribute to background noise. The Classroom Acoustic

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Standard (US): ANSI Standard S12.60 for Classroom Acoustics addresses the issues of both

reverberation time and background noise and their effect on speech intelligibility by placing

maximum permissible levels on each. Under the new standard, the maximum reverberation

time in an unoccupied, furnished classroom with a volume under 10,000 cubic feet is 0.6

seconds, and 0.7 seconds for a classroom between 10,000 and 20,000 cubic feet. The

maximum level of background noise allowed in the same classrooms is 35 decibels (dBA).

The standard’s acoustical performance criteria and design requirements apply during the

design and construction of all new classrooms or learning spaces of small-to-moderate size,

and, as far as is practical, to the design and reconstruction of renovated spaces.

Excessive noise in schools has a negative impact on student learning and performance

(Haines, Stansfeld, Job, Berglund, & Head, 2001). While a 1 decibel (dB(A)) change in

sound level is barely noticeable, background noises are perceived as doubling in loudness

every10 dB(A) (Muehleisen, N.D). Background noise in unoccupied classrooms should not

exceed 30-35 dB (A) (Crandell & Smaldino, 1999a; Accredited Standards Committee, 2002).

Major sources of background noise include:

HVAC noise (vents, ductwork, A/C unit)

Outdoor noise (automobiles, airplanes)

Reflected speech sounds (echo)

Noise from adjacent spaces

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Here the air borne sound is absorbed by the perforated patterns and special liners in the

ceiling elements or insulated with vertical bulk head. Studies of speech recognition confirm

that an adult listener hearing words in the context of a sentence can fill in words or syllables

that are not heard clearly, depending on the size of the listener's vocabulary. Since children

have smaller vocabularies, they are less able to fill in the words not heard clearly. Similarly,

someone using English as a second language or someone who suffers from an attention

deficit disorder is at a significant disadvantage in a noisy classroom. In addition, many

children with usually normal hearing have temporary hear losses from illness. Otitis Media, a

bacterial infection of the middle ear that is the most frequently-occurring childhood medical

complaint, has more than doubled in the last decade. Compounding the learning

disadvantages that confront children in noisy classrooms or with impaired hearing are the

constant discouragement and frustration that can inhibit the motivation of even the most

talented to learn and to excel. The importance of clearly hearing the teacher seems self-

evident, but this has not been a design criterion of many schools in the past.

Here sound absorbing materials is equal to 50-75% of the ceiling surface area. While in high

traffic areas, attempt to cover 75% of the ceiling surface area is advisable (Accredited

Standards Committee, 2002).

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2.2 classroom design for good hearing

Classrooms may be noisy simply because of the way they are constructed and finished. It is a

shocking fault, for the need to hear well is basic in education. In the summer of 2002, the

American National Standards Institute published Standard 12.60, a totally new standard that

provides acoustical performance criteria, design requirements and design guidelines for new

classrooms and renovation of existing classrooms. The goal is to ensure a high degree of

speech intelligibility in learning spaces. In order to achieve this, the noise level in an empty

classroom should be kept to less than 35 decibels, and reverberation or echoes controlled.

While the impetus for the standard began initially as an effort to improve schools for children

with impaired hearing or other learning disabilities, children with normal hearing will also

benefit greatly from these standards.

The good news for architects and builders is that compliance with the acoustical standards

need not be costly if they are incorporated early into the planning and design process,

although remodelling existing facilities could be expensive depending on the actual situation.

The requirements for good hearing were first presented formally to the American Institute of

Architects in 1898 and have been successfully applied to many schools. However, in the

absence of enforceable standards far too many schools have been built with little or no

concern for good hearing. Since acoustical problems are created by the design they can just as

easily be avoided by the design.

2.21 Requirements for good hearing in classrooms

   Two basic criteria must be satisfied to meet the requirements for good hearing:

A quiet background (e.g. noise from intruding traffic, adjacent classes, ventilation

systems etc.)

Control of reverberation and self-noise

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2.22 Examples of effective classroom design

     Designers and builders can improve hearing conditions in schools by incorporating the

basic principles of acoustics into classroom design. For every new and remodelled school, the

control of unwanted sounds and enhancement of wanted sounds, without the complications

inherent in general amplification should be placed high on the list of design goals. For new

classrooms accommodating from 30 to 40 children these requirements should not add

anything to the cost of either design or construction. However, correction of acoustical

deficiencies in existing facilities could be costly, depending on the particular situation.

At least the following considerations must be addressed:

Control of unwanted sounds

locate schools away from highways, rail tracks, and flight paths minimize noise intrusion from outdoors minimize interference between classrooms design quiet ventilation system

Enhancement of wanted sounds

control excessive reverberation by sound absorption minimize echoes from distant surfaces (such as the back wall) use hard materials for useful sound reflections (such as on surfaces beside and above

the teacher)

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3.0 INDOOR ACOUSTIC STANDARD OF FUTA

STAFF SECONDARY SCHOOL (CASE STUDY)

We will be basing our study on futa staff secondary school founded in 1992, by the federal

university of technology akure with the aim of catering for the education of the children of

futa staff community. So we are going to critically analyse the indoor acoustic standard of a

typical class room putting into consideration the floor, wall and ceiling finishes, plan of the

floor of the space showing furniture, materials and finishes, a ceiling plan of the space,

pictures showing the elevation of the interior space showing materials and finishes and

analysing sources of internal and external noise.

Figure 1: FUTA staff secondary school (Case study)

3.1 Site plan

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Figure 2: FUTA staff secondary school (Site plan showing sources of external noise)

Due to the nearness of the building to the main road, classrooms are exposed to vehicular

noise and they are no external barriers to protect the classrooms from the noise which

therefore makes the environment incondusive for learning.

Figure 3: picture showing possible source of external noise

3.2 Plan of internal space

The plan of a typical classroom is rectangular in shape 8220mmx9700mmx3000mm which

accommodates 36 students sitting in 6x6 arrangements. A rectangular cube provides better

acoustics for a classroom as illustrated below.

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Figure 4: floor plan showing the existing space (typical classroom showing furniture

arrangement)

3.3 Ceiling plan of internal space

The ceiling plan is a flat plane comprising of abestos and tyrod which is a good acoustic

material.It is strong, fire-resistant, flexible and a good thermal insulator

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Figure 4: picture showing the ceiling plan and existing ceiling of the existing space

Figure 5: picture showing the occurence of reverbration

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Figure 7: pictures showing the elevation of the interior space showing furniture arrangement

materials and finishes

The furnitures are made of hard plastic materials which is not a good acoustic material as it

casues reverbration due to hollows within the plastic material as such causes echoes that

interfers with speech intelligibility. Walls are finished with emulsion paint and floors are

finished with cement which is poor in acoustics as it tends to produce noise as people walk on

it.

4.0 PERCEPTION OF THE SPACE

Due to our research we discovered that the school is located in an inconvenient site. It is

located at the south gate of the federal university of technology akure ( FUTA). Secondly, we

discoverd the facility was poorly zoned according to noise because classrooms were placed

near the major sources of noise. Finally, we discoverd that they were no applications of

acoustic barriers to protect classrooms from noise which make it hard for speech

intelligibility.

4.1 Proposal for improving the indoor acoustic standard of a

classroom

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From our research the following proposals would help improve the indoor acoustic standard

of the existing classroom:

Separate particularly sound-sensitive spaces (e.g., classrooms, counsellling offices)

from both external and internal sources of noise (e.g playgrounds) by using non-

acoustically sensitive areas (corridors, storage spaces) as buffer space (Accredited

Standards Committee, 2002; Seep et al., 2000.

Rescheduling of activities by allocating time for noisy activities to be performed

together thereby creating more quiet time for lecture.

Improving the surface of the classrooms by using sound absorbing materials on

internal walls o f the classroom e.g. Acoustic panels.

Avoid placing adjoining doors on shared classroom walls, as this will limit sound

isolation (UK Department of Education and Skills, 2003a).

Reducing external background noise by making use of barriers externally e.g.

landscaping.

Avoid open-plan classrooms and classroom with thin or partial partition walls

between instruction areas to reduce sound transmission between rooms (Accredited

Standards Committe, 2002; Crandell & Smaldino,1999a).

5.0 CONCLUSION

In conclusion the study of acoustics in any human environment cannot be over emphasised

because acoustics is the science of sound. Noise is an element that can pose danger on

human health, safety and disturbance to human activities which automatically includes the

learning environment. Therefore a great deal of effort has to be made to ensure a suitable

learning environment for students. So our research on the indoor acoustic standard of futa

secondary school has lead us to draw up the above listed proposal for improving the acoustic

of any learning environment and also any other acoustic defficient environment.

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REFFERENCEBess, F. H. (1999). Classroom acoustics: An overview. The Volta Review 101(5), 1-14.

CertainTeed Ceilings. (2008). listening vs. hearing: Ceiling choices that make a difference

to a child’s

education. Retrieved July 16, 2009, from

http://archrecord.construction.com/schools/resources/0712/ CertainTeed.pdf

Crandell, C. C., & Smaldino, J. J. (1999b). Improving classroom acoustics: Utilizing

hearing-assistive technology and communication strategies in the educational setting. The

Volta Review, 101(5), 47-62.

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Muehleisen, R. T. (n.d.[a]). Basics of room acoustics. Unpublished manuscript. Retreived

by CISCA. 23-31.

Nelson, P. (2003). Sound in the classroom: Why children need quiet. ASHRAE Journal, 45,

22-28.

Pepi, F. (1999). Modifi cations to mainstream classrooms for children with cochlear

implants. CICI CONTACT,

13(2). Retrieved by CISCA.

Smaldino, J. J., & Crandell, C. C. (1999). Speech perception in the classroom. The Volta

Review, 101(5),

15-21.

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