Sound Insulation Tiles at School Help Calm Crying Children #ASA188

Sound Insulation Tiles at School Help Calm Crying Children #ASA188

Studying effects of sound absorption on classroom noise levels can help inspire regulations in Japan.

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NEW ORLEANS, May 23, 2025 – When children are dropped off at a school or day care for the first time, there can be a lot of feelings and sometimes meltdowns caused by being separated from parents, meeting new people, and hearing new noises. Could the architecture of the room help to soothe at least some of the children’s concerns?

“Classrooms without any sound absorption are the majority in Japan,” said Ikuri Matsuoka, a master’s student at Kumamoto University in Japan. “My motivation was to make people aware of the importance of acoustics in classrooms because in Japan, there are no standards or guidelines for acoustic design of preschool and school classrooms.”

Children in the process of developing language and speech can have a hard time listening, and so a classroom with lots of noise and reverberation can disturb communication and cause them to talk louder.

“We expect that preschool children entering school for the first time normally feel stressed by the difficulty of verbal communication,” Matsuoka said. “Therefore, this study examined whether sound absorption could mitigate such adverse effects.”

Sound Insulation

A classroom in Japan with polyester fiberboard tiles on the ceiling to promote sound absorption. Credit: Ikuri Matsuoka

To test the effect of sound absorption on children’s noise, Matsuoka installed polyester fiberboard, a type of sound-absorbing material, onto one classroom’s ceiling and compared it to another without any.

Matsuoka will present their findings Friday, May 23, at 1:40 p.m. CT as part of the joint 188th Meeting of the Acoustical Society of America and 25th International Congress on Acoustics, running May 18-23.

Matsuoka analyzed the indoor activities using video and audio to determine noise levels and the number of times the children cried. After six months, Matsuoka found that children were louder in the room without the insulation.

“During the experiment, I interviewed the four teachers in the four classes several times,” Matsuoka said. “Three of the four teachers answered that they felt the reverberation had changed, and one of them, a veteran teacher with 25 years of experience, answered that she felt clearly more comfortable talking to the children.”

To complement their results, Matsuoka and their professor also used artificial intelligence and machine learning to analyze the data automatically. They used an acoustic event detection method to identify children’s crying instead of manually scrubbing through the data. This work will also be presented during a session on “Materials for Sound Absorption, Diffusion, and Transmission Loss” on Friday, May 23, at 1:00 p.m. CT.

“We expect that machine learning will be necessary for long-term observations,” Matsuoka said. “From our research, we hope that those involved in both the child care and architectural fields recognize how important it is to have reduced reverberation that mitigate noisy atmosphere and promote clear verbal communication for children.”

——————— MORE MEETING INFORMATION ———————
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ABOUT THE ACOUSTICAL SOCIETY OF AMERICA
The Acoustical Society of America is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world’s leading journal on acoustics), JASA Express Letters, Proceedings of Meetings on Acoustics, Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. See https://acousticalsociety.org/.

ABOUT THE INTERNATIONAL COMMISSION FOR ACOUSTICS
The purpose of the International Commission for Acoustics (ICA) is to promote international development and collaboration in all fields of acoustics including research, development, education, and standardization. ICA’s mission is to be the reference point for the acoustic community, becoming more inclusive and proactive in our global outreach, increasing coordination and support for the growing international interest and activity in acoustics. Learn more at https://www.icacommission.org/.

Myth busted: classroom acoustics can be easy and cheap

Coralie van Reenen – cvreenen@csir.co.za

Council for Scientific and Industrial Research, Council for Scientific and Industrial Research, Gauteng, 0001, South Africa

Popular version of 3pAAb – Classroom acoustics: a case study of the cost-benefit of retrofitted interventions
Presented at the 185th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0023323

Please keep in mind that the research described in this Lay Language Paper may not have yet been peer reviewed.

Achieving the right acoustic conditions for classrooms is often dismissed by school planners as being too difficult or too expensive. This is to the detriment of students who are unable to hear the teacher properly, especially for children who are being taught in their second language, as is common in South Africa. This study proves that acoustic treatment need not be difficult or costly to achieve.

To refute the notion that acoustic improvements are expensive and specialized, this experimental case study was designed and carried out in a typical classroom in the small rural village of Cofimvaba in the Eastern Cape, South Africa. The ideal classroom environment has a low ambient noise level of 35 dB and a reverberation time below 0.7 seconds, but this classroom has a reverberation time of 1 second. Reverberation time refers to the time it takes for a noise to die down and essentially refers to how much a room echoes, which negatively affects speech clarity. The experimental intervention simulated the installation of floating ceiling islands by installing different materials on the roof of temporary gazebos in the classroom.

The four materials used were acoustic ceiling tiles which represent a typical solution and three DIY solutions using carboard egg cartons, thermal insulation batting, and sponge foam bed mattresses. Each material provided an improved reverberation time. The best performing was the sponge at 0.6 seconds, while the other three materials performed equally at 0.8 seconds.

The cost of each material was reduced to a rate per square meter. The most expensive material was the acoustic ceiling tiles at R 363.85/m2 while the cheapest was the egg cartons at R 22.22/m2, or less if they are available as waste items.

The availability of materials was evaluated in terms of the distance to supply and whether the product is available in a retail store or requires a special order and delivery. The batting is available from hardware stores nationwide and could be purchased by walk-in from the local hardware store, within a 2 km radius of the site. The egg cartons could be ordered online and delivered from a packaging company within a 150 km radius. The foam mattresses could be purchased by walk-in at a local retailer within a 5 km radius of the site. The acoustic ceiling tiles were ordered online and delivered from the warehouse within a 700 km radius of the site.

Using the weighted sum model and assigning equal weighting to each attribute of acoustic performance, cost, distance to supply, and walk-in availability, a performance score for each intervention material was calculated. The batting ranked number one, followed in order by the sponge, egg cartons and lastly acoustic tiles.

The case study demonstrates that an improvement in acoustic conditions of at least a 0.2 second reduction in reverberation time can be achieved without significant cost. Although the batting did not achieve the ideal reverberation time, when only the speech frequencies were considered, it fell within the recommended maximum of 0.7 seconds.

The recommended design intervention is a frame containing batting covered with a taught fabric and suspended from ceiling hooks, thus avoiding disruptive construction works. This shows that improved classroom acoustics can be achieved without high cost or technical difficulty.

Read more: Classroom acoustics: a case study of the cost-benefit of retrofitted interventions