Coalition for Classroom Acoustics' Response to Federal Access Board's Request for Information on Classroom Acoustics

This testimony was written by the Coalition for Classroom Acoustics in response to a Request for Information about acoustics and educational facilities from the Architectural and Transportation Barriers Compliance Board (aka the Federal Access Board). You can also look at testimony from the Acoustical Society of America.

For information on joining the Coalition for Classroom Acoustics, click here.

July 30, 1998

To: Office of Technical and Information Services Architectural and Transportation Barriers Compliance Board 1331 F Street NW. Suite 1000
Washington, DC 20004-1111

Subject: Request for Information on Acoustics 36 CFR Chapter XI [Docket No. 98-4]

Published in the Federal Register, June 1, 1998 From: Coalition for Classroom Acoustics STATEMENT OF THE COALITION IN RESPONSE TO RFI

We are a coalition of social and physical scientists, audiologists, health practitioners, educators, engineers, consumers and parents who often use different languages to work in our respective fields. However, there is one subject of great importance to our society where we have striven to find common language and purpose. The subject is the auditory learning environment.

In this statement we address verbal learning environments in our schools where many of our children, and especially those with hearing or learning disabilities, are being deprived of a clear communication channel because of inferior classroom acoustics.

Poor classroom communication acts as a barrier to learning, stunting intellectual growth, lowering self esteem, and serving to diminish the potential for the child to grow into a productive citizen.

Below, we discuss three overriding elements of direct relevance to the Request for Information of the "Access Board:"

1) Speech perception and hearing in the classroom,

2) classroom acoustics, and

3) benefits/costs to the society in assuring good classroom verbal communication.

We defer to individual member organizations of the Coalition to respond on a point by point basis to the eleven questions of the Board.

1. Speech Intelligibility, Hearing and Listening, and Learning.

Acoustic accessibility is simply access to spoken input in a manner which minimizes acoustical barriers such as noise, inadequate speech level (i.e. - distance), and reverberation. Because acoustic properties of classroom acoustics are invisible, their consideration is frequently overlooked in accessibility planning. The highly interactive teaching style practiced by most teachers today compared to didactic teaching styles of the past, emphasizes the importance of hearing peers and teachers in groups more often than one-on-one in the classroom.

Speech intelligibility is the prerequisite to auditory learning; therefore the "smearing" or masking of speech information caused when poor acoustic conditions exist, affects the entire chain of learning. Furthermore, the practice of including children with all types of learning difficulties in regular classrooms, "inclusion", has magnified the problem as these children struggle to attend, hear, listen, and learn in their classrooms everyday.

In the past, most of these children were educated in resource rooms for their primary academic subjects. Because participation in the regular classroom was primarily during non-academic activities, their hearing, attending, and listening problems were not as apparent. At the same time resource rooms were usually smaller with fewer children and the instruction and the environment much more controlled by the special education teacher so that these issues of acoustic accessibility were not as obvious or immediate.

In addition to those with hearing loss, there is a growing number of children who have been found to have speech perception problems in poor acoustic environments. This at-risk group includes: children younger than the age of 13 because their neurological system is not fully mature, children who have fluctuating hearing loss associated with ear infections, children who have articulation disorders, children who have language learning disorders, children who have learning disabilities, children who are non-native English speakers, and children who have central auditory processing disorders. Thus, in addition to all children under the age of 13, 8-10 % of the student population of all ages may have significant learning problems which will be exacerbated by poor classroom acoustics. The implications of not hearing adequately may be manifested in many ways but most often results in poor academic performance, self-esteem, and social interactions, the very foundations upon which student success is built.

2. Classroom Acoustics

The problem of good acoustics is a very broad one. For the purposes of this brief statement, we focus on the prototypical classroom of no more than 30-35 students, because the prototypical classroom is where most verbal interactions usually take place. For auditoria, cafeteria, gymnasiums, music rooms, offices, and the like, specific guidelines must also be defined.

In larger spaces where verbal communication is important (such as auditoria), and in the absence of a sound system, we rely on reflected sound to maintain the decibel level of the sound throughout the space. But in smaller spaces, the direct sound from teacher to student is at least as important, if not more important, than the indirect or reflected sound. In the intimate classroom environment, we can ask: What are the obstacles to verbal communication?

There are two obvious culprits which always must be controlled:

Excess noise and excess reverberation.

The issue is complicated by the distinction between the design of new classroom spaces and the remediation of existing spaces. For newly designed spaces, it is our responsibility to specify an architect/contractor's worksheet and checklist of good classroom acoustics design practice. We should also give concrete examples of good classroom design. Preparing such examples will be a research challenge for professionals in the period subsequent to the submission of this document. If these conservatively defined specifications and examples are followed carefully, then we should be confident that in a very large majority of the cases, the results will be successful or easily remediated.

For existing spaces requiring renovation, we need to specify performance standards that are both reasonably easy to specify and to measure. We should also generate a diagnostic checklist that suggests what remediation should take place, and we should be able to point to one or more sources for information on consultants and vendors who can supply services and/or equipment to bring the space into minimum standards for communication for all students.

Let us concern ourselves with the acoustical guidelines for new construction, since these will be the standards against which efforts at remediation will be compared. By understanding the environmental background noise, through an appropriate acoustical survey, architects and acousticians can work together to design school layout and classroom spaces 1) so that the external noise has minimal impact, 2) so that classrooms are sited away from noise-generating internal spaces, 3) so that wall and ceiling-floor partitions, windows, and doors are specified to achieve adequate acoustical isolation, and 4) so that, when appropriate, sound field amplification is available to maximize speech to noise ratios under suitable acoustic conditions.

Even in the absence of external noise, we must realize that we are our own noise sources. The sound we made a moment ago should not be reverberating around a space to mask the information we are currently conveying. Students make noise not only vocally, but also in their interaction with furniture, books and their peers. Fortunately, excess reverberation can be easily dealt with through the judicious use of acoustical treatment. There is no mystery in calculating the approximate amount of absorbing material required for a room of a given volume. If the classroom has been well designed, the ceiling will not be too high and therefore the room will not have an excessively large volume. Absorbing material to be used in a room is ordinarily placed on the ceiling with an adequate air space to assure acoustical control over a broad frequency range. Sometimes some upper wall treatment is desirable to mitigate flutter echo effects associated with hard parallel walls. Neither of these tasks is particularly difficult or costly, as is spelled out in responses by other members of the Coalition.

Reverberation control with absorbing material is more straightforward than controlling unwanted sound sources, such as heating, ventilating, and air conditioning sound, noisy fluorescent light fixtures, noises from sources external to the room, and self noise, as mentioned earlier.

It is generally known that there are three ways to control unwanted sound: at the source, along the path between sound source and receiver, and at the receiving end.

The last of these is not possible because it implies the use of earplugs, which only would be considered in particularly noise environments, such as a music practice space for bands and orchestras.

The first option, controlling sound at the source, can be accomplished by purchasing equipment with low noise ratings and by installing it properly. Treating the path along which noise propagates may entail anything from lining the ventilation ducts between a fan unit and the room, to assuring that doors are heavy enough and are properly gasketed, with drop seals, if necessary, to prevent hall noise from leaking in (and out). Providing acoustic treatment in halls also helps reduce noise levels transmitted into adjacent classrooms.

In the classroom, difficulties in hearing by a small group of children with special challenges are a warning that the classroom may not meet the minimum standards of classroom communication for all students. Although assistive listening devices and teacher amplification can improve one direction of the communication channel, learning requires the responses of students, and, therefore, electronic enhancements, which may be necessary in some instances, are not sufficient to guarantee clear and intelligible communication.

3. Societal Costs/Benefits

Because the deficits from poor learning environments are often not acute, they are usually not identified over the short term. However, the integrated effects of chronic hearing and listening barriers can be enormous over a child's elementary and secondary school years, with particularly severe deficits developing in the early years of education during language development and later, when academic content becomes complex.

Fortunately, there is excellent evidence, cited in responses by member organizations in the Coalition and by others, that the acoustical quality of classrooms relates far more to good design and careful implementation than to cost. There are many examples of high cost and poor acoustical results, and the converse. The problems have arisen, in part, because acoustical consultation and "treatment" have been considered an "add-on" rather than an essential component in the initial design phase. When budgets get tight, "add-ons" get jettisoned.

Yet the foundation of educational pedagogy is verbal communication. When taxpayers pay several thousand dollars per student per year in public education, it makes no sense to allow the verbal communication channel to be sabotaged. Letting this happen often results in students who do not or cannot pay attention, and in teachers who are unduly stressed by the additional effort exercised in order to promote an effective learning environment.

Moreover, when bad acoustics are a primary reason for prohibiting students with disabilities the opportunity to benefit from education or it increases the cost of education, the students and we are all poorer.

The members of the Coalition have much to offer through past, present, and future research into classroom learning environments. In particular, we see the need for further research to support the following activities:

1) Education of educators, public officials, designers, builders, and the general public of the role that good acoustics plays in learning and social development, and of the cost effectiveness of remediation of existing facilities with poor acoustics.

2) Training of designers and builders in good design and implementation practices through design checklists, through an inventory of a wide variety of detailed examples of good classroom practice, and through the provision of lists of professionals who can provide their expertise so that design goals are achieved in the most cost effective manner.

3) The development of strategies on how special needs can be addressed for children with hearing and learning disabilities by making use, when appropriate, of the latest advances in amplification and large area and personal assistive listening technologies.

In summary, the coalition members identified below strongly encourage the Access Board to develop and issue acoustical accessibility guidelines for classrooms and other learning facilities for the ultimate benefit of all students.

The undersigned wishes to acknowledge the assistance from: a) Cheryl Deconde Johnson, member of AAA, b) the members of the ASA Task Force on Classroom Acoustics and c) Evelyn Williams, member of ASHA, for their contributions in preparing this coalition response.

Respectfully submitted,

Prof. Robert E. Apfel

Visiting Professor of Architecture

Yale University

Faculty of Engineering

9 Hillhouse Ave.

New Haven, CT 06520-8286


Professional Organizations

Acoustical Society of America (ASA)

Alexander Graham Bell Association for the Deaf (AGBELL) American Academy of Audiology (AAA)

American Speech-Language-Hearing Association (ASHA) Educational Audiology Association (EAA)

National Council of Acoustical Consultants (NCAC)

Self Help for Hard of Hearing People (SHHH)

The Council of Educational Facility Planners, International (CEFPI)

Industry Organizations

Armstrong World Industries

Association of Wall and Ceiling Industries-International (AWCI) Ceiling and Interior Systems Construction Association (CISCA) Ecophon CertainTeed Inc.

International Cellulose Corp.


Janis (Widget) Richards, Parent

Mark E. Schaffer, Past Chair & Member, ASHRAE TC2.6 Sound and Vibration Committee Anne Seltz, MA CCC-A