May 29, 2001 Feature

An Update on Classroom Acoustics

Classroom acoustics have been shown to be a critical factor in the psychoeducational, psychosocial, and academic achievement of children with hearing loss and those with normal hearing. While the importance of good room acoustics has been known for decades, this factor has been often ignored, because there is no national standard for what constitutes an acceptable acoustic environment for listening and learning.

Thanks to the efforts of parents, audiologists, acoustical consultants, architects, acoustical materials manufacturers, professional organizations, educators, and consumers, a national standard is now nearing completion. In September 1999, the Access Board published a " Notice of Agency Action on Classroom Acoustics " in the Federal Register , following publication of a " Request for Information " in June 1998. The Access Board is that part of the U.S. government that develops guidelines for use by designers and builders so that buildings can meet the requirements of the Americans with Disabilities Act. In doing so, the Access Board acknowledged the input received from the many individuals and organizations cited above, and emphasized that noise and reverberation can pose a significant barrier to listening and learning in the classroom.

In concert with, but prior to, the action of the Access Board in the fall of 1997, a Working Group on Classroom Acoustics was commissioned by the Acoustical Society of America (ASA) through the American National Standards Institute (ANSI) to develop a draft standard for balloting by the ANSI/ASA committee responsible for noise issues (S-12). In March 2001, the draft proposal received approval by the ANSI Accredited Standards Committee S-12 on the initial ballot. The standard is still in draft form, awaiting negotiation leading to approval by ANSI. The standard sets forth both performance and design criteria for acceptable learning spaces. It is hoped that the standard will make classrooms acoustically satisfactory.

The proposed standard contains criteria for noise and reverberation in educational settings similar to those in the 1995 ASHA position statement on acoustics in educational settings. The proposed ANSI/ASA standard contains criteria for noise and reverberation in classrooms as follows:

1. Unoccupied background noise
30 dBA
35 dBA
2. Reverberation
0.4 sec
0.6– 0.7 sec*
3. Noise Criteria Curve
NC 20
NC 30
4. Preferred signal-to-noise ratio
* Reverberation time in unoccupied classrooms must not exceed 0.6 seconds in classrooms of 10,000 cubic feet or less, and 0.7 seconds in classrooms with volumes between 10,000 and 20,000 cubic feet.

It is hoped that the Access Board will adopt this new ANSI/ASA standard as its guideline to meet ADA requirements and, therefore, reduce the barriers to accessible communication and learning currently caused by excessive noise and reverberation.

ASHA has been asked by the Access Board to cosponsor the production of a cable network series videotape on school construction, which will include a focus on classroom acoustics. The ASHA Executive Board approved a resolution to contribute $5,000 in funding for the video, which is now being produced by the Information Television Network (iTV) for a cable network series on technology. The video will be aired on CNBC and in syndication on America One cable, and will be available on the Internet for one year. Susan Brannen, ASHA ’ s vice president for professional practices in audiology, was instrumental in gaining support for the resolution. " We are hopeful that the video will facilitate a shift in thinking for architects and school administrators, " Brannen said. " Our children need to have optimal auditory access to meet the increasing challenges in the classroom. "


Crandell served as an ASHA liaison to the Acoustical Society of America Working Group on Classroom Acoustics from June 1999 – December 2000. The authors have written a number of publications and grants on the topic of classroom acoustics. In addition, they both present on this topic around the world.

Carl Crandell, is associate professor of audiology, department of communication sciences and disorders, University of Florida in Gainesville. Contact him by email at

Joseph Smaldino, is professor of audiology in the department of communicative disorders at the University of Northern Iowa in Cedar Falls. Contact him by email at

cite as: Crandell, C.  & Smaldino, J. (2001, May 29). An Update on Classroom Acoustics. The ASHA Leader.


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