Many classrooms have bad acoustics that inhibit learning

December 20, 1999

COLUMBUS, Ohio -- Researchers at Ohio State University have found that the acoustics of many classrooms are poor enough to make listening and learning difficult for children.

The study of 32 classrooms in central Ohio primary schools found that only two met the standards recommended by the American Speech-Language-Hearing Association (ASHA).

"This is probably the most extensive acoustical study of classrooms ever," said Lawrence Feth, professor of speech and hearing science at Ohio State.

The findings held across economic boundaries. In rural, urban, and suburban classrooms -- old school buildings and new -- background noise and echoes were prominent enough to hamper the learning of children with even mild hearing problems, according to the ASHA recommended levels.

"One of the worst classrooms was in a school district that had some of the better classrooms," said Gail Whitelaw, adjunct associate professor of speech and hearing science. "So you can't just say the acoustics in a district are good or bad. It varies by the room. It's like real estate -- what matters is location, location, location."

The researchers pointed to previous studies which showed that children's learning and speech capability is hindered when they can't hear well in the classroom.

Feth explained that sound bounces off of hard surfaces, and classrooms normally have hard floors and walls. "When sound bounces around it creates its own masking noise, and interferes with understanding speech," he said.

Whitelaw said that children are sensitive to bad acoustics because they are still learning language, while adults' larger vocabulary helps them mentally compensate when they can't hear clearly.

"It only takes a small change in speech to noise ratio for a child to go from understanding almost everything to understanding very little," said Feth.

Children with hearing problems or for whom English is a second language have an especially hard time following what a teacher says in a noisy room, the researchers said.

"Even if kids have temporary hearing loss from an ear infection, and even if it's intermittent, it presents a big problem for understanding speech in a noisy environment," said Feth.

Heather Knecht, formerly a graduate student, initiated this project, and Whitelaw and Feth were her advisors. Knecht, now a practicing speech-language pathologist in Dayton, Ohio, presented these results recently in Columbus at a meeting of the Acoustical Society of America.

Knecht measured the background noise level and reverberation time in 32 randomly chosen classrooms in eight central Ohio schools, some public, some private.

The ASHA guidelines recommend that sounds dissipate in 0.4 seconds or less, and that background levels not rise above 30 decibels(A). Feth said the decibel(A), or dB(A), unit is different than a plain decibel in that the dB(A) gives more weight to frequencies between 500 and 3,000 Hertz -- the ones that most affect how humans perceive loudness.

Feth said typical background noise in an office would average about 60 dB(A). Previous research has shown that noise in classrooms often rises to the same level.

Knecht measured background noise in empty classrooms after school hours to record the bare minimum sound level. Then, with a combination sound generator and sensor, she created a 120-decibel boom in each classroom, and measured the amount of time the sound took to dissipate. Feth characterized 120 decibels as what someone would hear standing right in front of the speakers at a rock concert.

Only two of the 32 classrooms Knecht tested met the ASHA guidelines for both background noise level and reverberation time. The background noise ranged from a low of 28 dB(A) to a high of 68 dB(A). The shortest time for reverberations to dissipate was 0.2 seconds, the longest time 1.27 seconds.

Background noise and reverberation weren't necessarily connected, the researchers found. For example, one room had a reverberation time of 0.4 seconds -- within ASHA guidelines -- but a background noise level of 50.3 dB(A) -- more than 20 dB(A) too high.

Feth said the biggest single source of background noise in classrooms is the heating and cooling system, because many schools have opted for individual units instead of quieter central air.

Carpeting also helps buffer sound, but may be hazardous to children with allergies or asthma. For $1000 per classroom, a commercially available assistive listening system could do the trick, but that might be too expensive for some schools. Feth and Whitelaw listed some less expensive alternatives, such as draperies, wall hangings, or sound-absorbing panels.

"Educational audiologists perceive these changes as standard fare," said Whitelaw, "but for school administrators it's still a hard sell, because if they have to pull that money out of their budget, where will it come from?"

Whitelaw and Feth will continue this research, focusing on the relationship between room size and sound quality. They also want to find out whether the teachers who work in classrooms with poor sound quality experience more voice fatigue and take more sick days because they can't talk.

Brüel & Kjœr, a maker of sound and vibration equipment, provided the testing instruments for this study.
-end-
Contact: Lawrence Feth, (614) 292-1643;
Feth.1@osu.edu
Gail Whitelaw, (614) 292-6251;
Whitelaw.1@osu.edu
Written by Pam Frost, (614) 292-9475;
Frost.18@osu.edu

Ohio State University

Related Learning Articles from Brightsurf:

Learning the language of sugars
We're told not to eat too much sugar, but in reality, all of our cells are covered in sugar molecules called glycans.

When learning on your own is not enough
We make decisions based on not only our own learning experience, but also learning from others.

Learning more about particle collisions with machine learning
A team of Argonne scientists has devised a machine learning algorithm that calculates, with low computational time, how the ATLAS detector in the Large Hadron Collider would respond to the ten times more data expected with a planned upgrade in 2027.

Getting kids moving, and learning
Children are set to move more, improve their skills, and come up with their own creative tennis games with the launch of HomeCourtTennis, a new initiative to assist teachers and coaches with keeping kids active while at home.

How expectations influence learning
During learning, the brain is a prediction engine that continually makes theories about our environment and accurately registers whether an assumption is true or not.

Technology in higher education: learning with it instead of from it
Technology has shifted the way that professors teach students in higher education.

Learning is optimized when we fail 15% of the time
If you're always scoring 100%, you're probably not learning anything new.

School spending cuts triggered by great recession linked to sizable learning losses for learning losses for students in hardest hit areas
Substantial school spending cuts triggered by the Great Recession were associated with sizable losses in academic achievement for students living in counties most affected by the economic downturn, according to a new study published today in AERA Open, a peer-reviewed journal of the American Educational Research Association.

Lessons in learning
A new Harvard study shows that, though students felt like they learned more from traditional lectures, they actually learned more when taking part in active learning classrooms.

Learning to look
A team led by JGI scientists has overhauled the perception of inovirus diversity.

Read More: Learning News and Learning Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.