Classroom noise Classroom noise and its effects on and its effects on

classroom classroom learninglearning

School Noise Action Group School Noise Action Group (SNAG)(SNAG)

SNAG MembersSNAG Members Murray Hodgson, Professor of Acoustics and Noise Control, Murray Hodgson, Professor of Acoustics and Noise Control,

UBCUBC Janet Jamieson, Professor, Faculty of Education, UBCJanet Jamieson, Professor, Faculty of Education, UBC Tom Tylka, Teacher of the Deaf and Hard of Hearing, Tom Tylka, Teacher of the Deaf and Hard of Hearing,

Vancouver School DistrictVancouver School District Maureen Clarke, Teacher of the Deaf and Hard of Hearing, Maureen Clarke, Teacher of the Deaf and Hard of Hearing,

North Van School DistrictNorth Van School District Bev McKenna, Teacher of the Deaf and Hard of Hearing, Bev McKenna, Teacher of the Deaf and Hard of Hearing,

Burnaby School DistrictBurnaby School District Les King, Director of Facilities, Vancouver School BoardLes King, Director of Facilities, Vancouver School Board Mark Keelan, Health and Safety Officer, BCTFMark Keelan, Health and Safety Officer, BCTF Karin Bernauer, Teacher, Vancouver School DistrictKarin Bernauer, Teacher, Vancouver School District Linda Rammage, Director, Provincial Voice Care Resource Linda Rammage, Director, Provincial Voice Care Resource

Program Program Glynnis Tidball, Audiologist, St. Paul’s HospitalGlynnis Tidball, Audiologist, St. Paul’s Hospital Greg Johnson, Architect, Marceau Evans Johnson ArchitectsGreg Johnson, Architect, Marceau Evans Johnson Architects Kathy Pickford, Principal, University Hill Elementary Kathy Pickford, Principal, University Hill Elementary

Goals of SNAGGoals of SNAG Examine research that outlines the Examine research that outlines the

effects of noise in learning environmentseffects of noise in learning environments Increase awareness of acoustic issues in Increase awareness of acoustic issues in

educational settingseducational settings Inform school personnel, government Inform school personnel, government

officials, and the public of the benefits of officials, and the public of the benefits of quality classroom acousticsquality classroom acoustics

Develop local research projects to Develop local research projects to demonstrate the benefits of improved demonstrate the benefits of improved classroom acousticsclassroom acoustics

Lobby the provincial government to Lobby the provincial government to adopt classroom acoustic standardsadopt classroom acoustic standards

Current Issues:Current Issues:

What is classroom noise?What is classroom noise? Why classroom noise is a concern?Why classroom noise is a concern? What can be done to improve What can be done to improve

classroom acoustics?classroom acoustics?

NoiseNoise

Noise defined as unwanted soundNoise defined as unwanted sound Extremely high levels of noise can Extremely high levels of noise can

cause hearing damage (Occupational cause hearing damage (Occupational Health and Safety)Health and Safety)

Moderate levels of noise interfere Moderate levels of noise interfere with effectiveness and ease of with effectiveness and ease of communicationcommunication

How noise is measuredHow noise is measured Sound levels measured in decibels (dB)Sound levels measured in decibels (dB) 3 dB increase represents a doubling of 3 dB increase represents a doubling of

intensityintensity E.g., 35 dBA + 35 dBA = 38 dBAE.g., 35 dBA + 35 dBA = 38 dBA

Does not correlate to what we perceiveDoes not correlate to what we perceive 3 dB increase is just barely noticeable3 dB increase is just barely noticeable 10 dB increase will sound 2 x as loud10 dB increase will sound 2 x as loud 20 dB increase will sound 4 x as loud20 dB increase will sound 4 x as loud

Cannot estimate sound intensity by Cannot estimate sound intensity by what we hear!what we hear!

Decibel level of common Decibel level of common soundssounds

Sound sourcesSound sources SPL (dBA)SPL (dBA)

Faintest audible soundFaintest audible sound 00

WhisperWhisper 2020

Quiet residenceQuiet residence 3030

Soft stereo in residenceSoft stereo in residence 4040

Speech rangeSpeech range 50-7050-70

CafeteriaCafeteria 8080

Band classBand class 8888

P.E. classP.E. class 8989

Accelerating motorcycleAccelerating motorcycle 100100

Rock concertRock concert 120120

Jet engine (75 feet away)Jet engine (75 feet away) 140140

Sources of noise in the Sources of noise in the classroomclassroom

Outside noise sourcesOutside noise sources VehiclesVehicles VoicesVoices

Inside sources:Inside sources: Student activityStudent activity Equipment: computers, projectorsEquipment: computers, projectors Reverberation (echo) of sound within the Reverberation (echo) of sound within the

roomroom Neighbouring classroomsNeighbouring classrooms Ventilation and heating systemsVentilation and heating systems

Signal-to-noise ratio Signal-to-noise ratio (SNR)(SNR)

Signal-to-noise ratio (SNR): Signal-to-noise ratio (SNR): difference in dB between the speech difference in dB between the speech

(signal) and the noise(signal) and the noise Example:Example:

Teacher’s voice (signal) = 60 dBATeacher’s voice (signal) = 60 dBA Background noise = 45 dBABackground noise = 45 dBA SNR = 60-45 = +15 dBSNR = 60-45 = +15 dB

What might good SNR What might good SNR sound like?sound like?

1. Microphone placed on body of 1. Microphone placed on body of listener,listener,

12 feet from the sound source12 feet from the sound source

2. Microphone placed on lapel of 2. Microphone placed on lapel of talkertalker

- Linda Thibodeau, http://ahrc.utdallas.edu/online/- Linda Thibodeau, http://ahrc.utdallas.edu/online/

““I am a dynamic figure, often I am a dynamic figure, often seen scaling walls and seen scaling walls and crushing icecrushing ice.”.”

- Essay by Hugh Gallagher- Essay by Hugh Gallagher

What SNR’s do children What SNR’s do children need?need?

Depends on age of childDepends on age of child SNR (dB) required to achieve 95% speech SNR (dB) required to achieve 95% speech

intelligibilityintelligibility Grade 1: +15.5Grade 1: +15.5 Grade 3: +12.5Grade 3: +12.5 Grade 6: +8.5 Grade 6: +8.5 Young adults (lab): +1 Young adults (lab): +1

SNR of +10 dBSNR of +10 dB 1 in 10 words not understood by Grade 1’s on 1 in 10 words not understood by Grade 1’s on

averageaverage

- Bradley, 2005- Bradley, 2005

Speech understanding in Speech understanding in younger childrenyounger children

Auditory system still developingAuditory system still developing Children’s auditory system not fully developed Children’s auditory system not fully developed

until late teens (until late teens (++ 15 yrs) 15 yrs) Children do not process sound as well as older Children do not process sound as well as older

children/adultschildren/adults Knowledge base of language not fully Knowledge base of language not fully

developeddeveloped Don’t have language skills/knowledge to fill in Don’t have language skills/knowledge to fill in

the missing piecesthe missing pieces Children rely more on “bottom-up” processingChildren rely more on “bottom-up” processing

Younger children require better signal Younger children require better signal quality to understand speech wellquality to understand speech well

Double JeopardyDouble Jeopardy

Noise has more detrimental effect onNoise has more detrimental effect on Children learning in non-native languageChildren learning in non-native language

ESL, immersionESL, immersion Children with learning disabilitiesChildren with learning disabilities Children with behavioural, attentional Children with behavioural, attentional

difficultiesdifficulties Hard-of-hearing children (temporary, Hard-of-hearing children (temporary,

permanent) permanent) Cumulative effects?Cumulative effects?

Ideal listening Ideal listening environmentenvironment

Teacher’s voice is clearly audibleTeacher’s voice is clearly audible Little background noiseLittle background noise Good room acousticsGood room acoustics

Good attenuation of sound from outside Good attenuation of sound from outside noise sourcesnoise sources

Reverberation (“echo”) in the classroomReverberation (“echo”) in the classroom Not too little, not too muchNot too little, not too much

Acoustic characteristics of Acoustic characteristics of the ideal listening the ideal listening

environmentenvironment Recommended noise level of Recommended noise level of

unoccupied classroom:unoccupied classroom: ANSI S12.60: 35 dBAANSI S12.60: 35 dBA

Teacher’s voice (relaxed)Teacher’s voice (relaxed) 60 dBA60 dBA

Reverberation time (RT) between 0.4 Reverberation time (RT) between 0.4 and 0.6 secand 0.6 sec

SNR +15 dB SNR +15 dB

Are the acoustic conditions Are the acoustic conditions of our classrooms of our classrooms

adequate?adequate? In general, no!In general, no!

Noise, reverberation time & estimated Noise, reverberation time & estimated speech intelligibility (RaSTI) in most speech intelligibility (RaSTI) in most occupied classrooms are unacceptable occupied classrooms are unacceptable (ASHA, 1990; Pekkarinen & Viljanen, 1990)(ASHA, 1990; Pekkarinen & Viljanen, 1990)

Average levels from 43 classrooms Average levels from 43 classrooms (Bradley, 2005)(Bradley, 2005) Teacher’s voice (signal): 59.5 dBA (+ 5.5 )*Teacher’s voice (signal): 59.5 dBA (+ 5.5 )* Noise: 49 dBA (Noise: 49 dBA (++ 7.3)* 7.3)* Mean SNR: +11 dBMean SNR: +11 dB

SNR in Canadian SNR in Canadian classrooms (Bradley, 2005)classrooms (Bradley, 2005)

For Grade 1, 9.1% had ideal SNRFor Grade 1, 9.1% had ideal SNR For Grade 3, 39.9%For Grade 3, 39.9% For Grade 6, 51.5%For Grade 6, 51.5%

Effects of poor SNREffects of poor SNR

StudentsStudents Poor understandingPoor understanding Decreased attentionDecreased attention Decreased performanceDecreased performance

Reading deficienciesReading deficiencies Reduced motivationReduced motivation Delayed language acquisitionDelayed language acquisition

TeacherTeacher Contributes to increased vocal strain by teachersContributes to increased vocal strain by teachers

OtherOther Fewer verbal interactions between teachers, studentsFewer verbal interactions between teachers, students More time spent repeating instructions/information and More time spent repeating instructions/information and

less material coveredless material covered

Impact of poor acoustic Impact of poor acoustic environment on teachers’ environment on teachers’

voicesvoices Teachers must adjust voices to be Teachers must adjust voices to be

audible above background noise > 40 audible above background noise > 40 dBdB

Vocal adjustments contribute to Vocal adjustments contribute to increased vocal fatigue/strainincreased vocal fatigue/strain

Teachers with occupational voice Teachers with occupational voice problems problems Teacher’s voice quality and therefore the Teacher’s voice quality and therefore the

speech signal are compromised, resulting in speech signal are compromised, resulting in a poorer student performancea poorer student performance

Occupational hazard?Occupational hazard?

Teachers make up 3.8% of the population in Teachers make up 3.8% of the population in BCBC

Approximately 17% ofApproximately 17% of patients seen for voice patients seen for voice disorders at the Pacific Voice Clinic (VGH) are disorders at the Pacific Voice Clinic (VGH) are teachersteachers

A disproportionate number of teachers A disproportionate number of teachers experience voice problemsexperience voice problems

Voice problems may lead toVoice problems may lead to Teachers requiring time off workTeachers requiring time off work Occupational injury claimsOccupational injury claims

Summary of effects of Summary of effects of classroom acousticsclassroom acoustics

Poor classroom acousticsPoor classroom acoustics are a significant barrier to learningare a significant barrier to learning have the greatest impact on younger have the greatest impact on younger

children and those with special learning children and those with special learning requirements requirements

contribute to the high incidence of voice contribute to the high incidence of voice disorders among teachersdisorders among teachers

What can be done?What can be done?

Reduce noise levels in the classroomReduce noise levels in the classroom Identify and address noise sources where Identify and address noise sources where

possiblepossible Acoustic treatment of roomsAcoustic treatment of rooms

Increase signal qualityIncrease signal quality Sound field amplification (not necessarily Sound field amplification (not necessarily

helpful if reverberation is excessive)helpful if reverberation is excessive) Vocal/speech strategies for teachersVocal/speech strategies for teachers

Mandate acoustic standards in the BC Mandate acoustic standards in the BC school building codeschool building code

New and renovated New and renovated schoolsschools

Increase awareness of classroom acoustics and Increase awareness of classroom acoustics and noise issues among architects, school officials and noise issues among architects, school officials and administratorsadministrators

Locate new schools away from noise sources Locate new schools away from noise sources (traffic)(traffic)

Apply ANSI standards in the BC school building Apply ANSI standards in the BC school building codecode

Design with appropriate room size, ceiling height, Design with appropriate room size, ceiling height, sound separation between roomssound separation between rooms

Ventilation fans outside of the classroomVentilation fans outside of the classroom Appropriate use of absorptive vs. reflective Appropriate use of absorptive vs. reflective

materials to keep reverberation times between 0.4 materials to keep reverberation times between 0.4 and 0.6 sec.and 0.6 sec.

Existing schoolsExisting schools

Reduce interior noise sourcesReduce interior noise sources Classroom managementClassroom management Tennis balls on the feet of chairs and desksTennis balls on the feet of chairs and desks

Improve reverberation and sound Improve reverberation and sound absorption:absorption: Acoustic tiles, carpetingAcoustic tiles, carpeting Improve sound separation between Improve sound separation between

classrooms, hallwaysclassrooms, hallways WindowsWindows

ConclusionConclusion

Excessive noise and reverberation are significant Excessive noise and reverberation are significant barriers to effective learning, particularly for barriers to effective learning, particularly for younger children and those with special learning younger children and those with special learning needsneeds

An adult may not fully appreciate students’ level An adult may not fully appreciate students’ level of difficulty in a classroom situation because of difficulty in a classroom situation because adults hear better in noise than children doadults hear better in noise than children do

SNR of +15 dB is critical for an optimal learning SNR of +15 dB is critical for an optimal learning environmentenvironment

Excessive noise in the classroom contributes to Excessive noise in the classroom contributes to vocal strain in teachersvocal strain in teachers

Classroom noise and acoustics needs to be Classroom noise and acoustics needs to be properly addressed during the design, building properly addressed during the design, building and retrofitting of schoolsand retrofitting of schools

What needs to be done?What needs to be done?

Incorporate classroom ANSI Incorporate classroom ANSI acoustic standards into provincial acoustic standards into provincial school building standardsschool building standards

Ensure that contributions of noise to Ensure that contributions of noise to teacher voice problems are teacher voice problems are recognized by 3recognized by 3rdrd party insurers party insurers

Additional informationAdditional information ASA: ANSI S12.60 (2002) Classroom acoustics standardASA: ANSI S12.60 (2002) Classroom acoustics standard

http://www.asa.aip.orghttp://www.asa.aip.org Lay paper on classroom acoustics:Lay paper on classroom acoustics:

www.cllrnet.ca/Docs/RESOURCES/Lay_paper_02_internwww.cllrnet.ca/Docs/RESOURCES/Lay_paper_02_international-modified.pdfational-modified.pdf

CAA-ACA: Canadian Acoustical Association:CAA-ACA: Canadian Acoustical Association: http://www.caa-aca.ca/http://www.caa-aca.ca/

Canadian acoustical consultants et al.Canadian acoustical consultants et al. http://www.caa-aca.ca/MainFrame.htmhttp://www.caa-aca.ca/MainFrame.htm

IRC/NRC:Acoustical design of rooms for speechIRC/NRC:Acoustical design of rooms for speech http://www.infosource.nrc-cnrc.gc.ca/reports/ctus/http://www.infosource.nrc-cnrc.gc.ca/reports/ctus/

ctu51e.pdfctu51e.pdf