Group Sounds Alarm on School Acoustics
Warning that noisy classrooms with poor acoustics are hindering learning and harming teachers’ health, experts are urging Canada to adopt national sound standards for new schools and to improve listening environments for existing schools.
An average empty classroom’s background noise measures about 50 decibels (dB). It comes from sources such as outside traffic and schoolyard activities, hallways and neighbouring rooms, equipment like computers and projectors, and lighting, ventilation, and heating systems.
Add another approximately 10 dB from typical student activity, and the total background noise is 60 dB. That effectively covers up the teacher’s voice, since conversational speech is about 60 dB.
“Often in classrooms, with all the background noise, to be heard the teacher has to raise her voice and that results in voice problems,” said Maureen Clarke representing the Canadian Association of Educators of the Deaf and Hard of Hearing
Grade one children need a speech-to-noise ratio of 15.5 dB to understand what the teacher is saying, Ms. Clarke explained. This means teachers must speak 15.5 dB louder than the background noise.
“We want to help children learn at their potential,” said Linda Walsh, president of the Canadian Association of Speech-Language Pathologists and Audiologists. “When children don’t hear the teachers’ instructions in the first place, they’re not going to develop language skills and literacy skills according to how they should.”
Constantly striving to be heard leads to vocal fatigue, loss of voice, and other health problems in many of the teachers being treated by speech pathologists across Canada, Ms. Walsh said.
Ms. Walsh and Ms. Clarke are spokespersons for the Concerned About Classrooms Coalition, consisting of 18 national and provincial organizations working to enhance children’s learning environments and teachers’ vocal health.
The issue concerns not only children with hearing loss but also those with attentional and learning problems, or those learning in a second language. Even children with normal hearing are affected, said Ms. Walsh.
Research by John Bradley of the Canadian Language and Literacy Research Network found that “in a typical grade 1 classroom, the average student will not understand one in six simple, familiar, and clearly spoken words. However “in quieter conditions they can understand almost all of these words.”
The 2005 research also reported that less than 10 percent of Canadian grade one classrooms had the ideal conditions for students to hear all of their teacher’s words.
If they can’t hear clearly, students may not comprehend what’s being taught, or may misinterpret instructions. In particular, young children do not have the language knowledge or life experience to “fill in the blanks” when they hear only part of a word or sentence, says the coalition.
Education is under provincial jurisdiction, but Canada currently has no provincial building standards regarding classroom acoustics.
The coalition wants the federal government to develop national classroom construction standards so that new schools will be built with concern for sound and hearing. It’s also asking existing schools to assess their classrooms and make changes to improve the listening environment.
“We’re looking for the federal government to encourage the provincial governments to take action on this,” said Ms. Walsh.
The coalition is recommending that Canada adopt a U.S. standard approved by the American National Standards Institute (ANSI).
Developed by the Acoustical Society of America and the U.S. Access Board, the ANSI standard specifies a maximum background noise of 35 to 40 dB and a maximum reverberation time of 0.6 to 0.7 seconds for typical-size empty classrooms.
Reverberation time is how long it takes for sound to die away as it’s absorbed by interactions with surfaces in the room.
For general-purpose auditoriums used for both speech and music, reverberation times of 1.5 to 2.5 seconds allow a richer, fuller musical sound. But classrooms need much shorter times to ensure clarity of speech.
Sound field amplification is one possible solution for improving acoustics in existing classrooms. The teacher wears a microphone and speakers project the teacher’s voice around the classroom.
Ms. Walsh noted a 2007 New Brunswick study with kindergarten through grade 3 children which found that students in classrooms with amplification did much better on comprehension tests compared to those in classrooms without amplification.
Other solutions include using hypo-allergenic carpeting, hanging up curtains and cork boards, adding felt pads under chair and table legs, installing acoustic tiles, and putting up barriers to help absorb sound.
Last Friday the coalition held a press conference on Parliament Hill to urge federal action. Over the coming weeks it will continue the lobbying with provincial governments.
“We want children to have every advantage that they would need in order to be successful,” said Ms. Clarke.