[Federal Register Volume 64, Number 215 (Monday, November 8, 1999)]
[Proposed Rules]
[Pages 60753-60758]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-28941]


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ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD

36 CFR Chapter XI

[Docket No. 98-4]


Response to Petition for Rulemaking on Classroom Acoustics

AGENCY: Architectural and Transportation Barriers Compliance Board.

ACTION: Response to petition for rulemaking on classroom acoustics.

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SUMMARY: This document responds to a petition for rulemaking on 
classroom

[[Page 60754]]

acoustics. The Architectural and Transportation Barriers Compliance 
Board (the Access Board) will support the development of a standard on 
classroom acoustical design by the American National Standards 
Institute (ANSI) Committee on Noise (S-12), under the secretariat of 
the Acoustical Society of America (ASA). Resources and technical 
assistance on classroom acoustics are provided in this document.

FOR FURTHER INFORMATION CONTACT: Lois Thibault, Office of Technical and 
Information Services, Architectural and Transportation Barriers 
Compliance Board, 1331 F Street NW., suite 1000, Washington, DC 20004-
1111. Telephone number (202) 272-5434 extension 132 (voice); (202) 272-
5449 (TTY). These are not toll-free numbers. Electronic mail address: 
[email protected].

SUPPLEMENTARY INFORMATION:

Availability of Copies and Electronic Access

    Single copies of this publication may be obtained at no cost by 
calling the Access Board's automated publications order line (202) 272-
5434, by pressing 2 on the telephone keypad, then 1, and requesting 
publication C-12. Persons using a TTY should call (202) 272-5449. 
Please record a name, address, telephone number and request publication 
C-12. This document is available in alternate formats upon request. 
Persons who want a copy in an alternate format should specify the type 
of format (cassette tape, Braille, large print, or computer disk). This 
document is also posted on the Board's Internet site at http://
www.access-board.gov/rules/acoustic2.htm.

Background

    The Architectural and Transportation Barriers Compliance Board 
1 (Access Board) is responsible for developing accessibility 
guidelines under the Americans with Disabilities Act of 1990 (ADA) to 
ensure that new construction and alterations of facilities covered by 
the law are readily accessible to and usable by individuals with 
disabilities. The Access Board initially issued the Americans with 
Disabilities Act Accessibility Guidelines (ADAAG) in 1991. The 
guidelines contain scoping provisions and technical specifications for 
designing elements and spaces that typically comprise a building and 
its site so that individuals with disabilities will have ready access 
to and use of a facility. Although ADAAG contains a number of 
provisions for access to communications, including requirements for 
text telephones, assistive listening systems, and visible alarms, it 
does not include provisions for the acoustical design or performance of 
spaces within buildings and facilities.
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    \1\ The Access Board is an independent Federal agency 
established by section 502 of the Rehabilitation Act (29 U.S.C. 792) 
whose primary mission is to promote accessibility for individuals 
with disabilities. The Access Board consists of 25 members. Thirteen 
are appointed by the President from among the public, a majority of 
who are required to be individuals with disabilities. The other 
twelve are heads of the following Federal agencies or their 
designees whose positions are Executive Level IV or above: The 
departments of Health and Human Services, Education, Transportation, 
Housing and Urban Development, Labor, Interior, Defense, Justice, 
Veterans Affairs, and Commerce; the General Services Administration; 
and the United States Postal Service.
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    On April 6, 1997, the Access Board received a petition for 
rulemaking from a parent of a child with a hearing loss, requesting 
that ADAAG be amended to include new provisions for acoustical 
accessibility in schools for children who are hard of hearing. Several 
acoustics professionals, parents of children with hearing impairments, 
individuals who are hard of hearing, and a coalition of organizations 
representing them had also urged the Board to consider research and 
rulemaking on the acoustical performance of buildings and facilities, 
in particular school classrooms and related student facilities.
    On June 1, 1998, the Board published a Request for Information 
(RFI) in the Federal Register to gather public input on this issue (63 
FR 29679). The Board sought comment on a variety of issues in the 
notice and indicated that it would determine a course of action after 
evaluating responses to the notice. Alternatives included research, 
rulemaking, and technical assistance on acoustical issues. 
Approximately 100 comments were received in response to the RFI. The 
preponderance of the comments were from parents of children with 
hearing impairments and from professionals in acoustics and audiology. 
Few comments were received from school systems.
    A Board review of classroom acoustics also identified several key 
issues. A third of the school systems cited in a 1995 General 
Accounting Office study reported that acoustics for noise control was 
their most serious environmental concern. Studies of elementary and 
secondary school classrooms revealed that excessive background noise, 
which competes with the speech of teachers, aides, classmates, and 
audio educational media, is common even in new classrooms. School 
construction is again on the increase and much public and governmental 
attention is now being focused on education issues.

Comments

    Commenters submitted research which showed how high levels of 
background noise in classrooms compromise speech intelligibility for 
children with hearing loss and other auditory disabilities and limit 
the effectiveness of assistive technologies (such as hearing aids, FM 
systems, and soundfield amplification) for such students, so that their 
reading, communication, and learning skills may not develop adequately.
    Audiologists noted that children, because they are neurologically 
immature and lack the experience necessary to predict from context, are 
inefficient listeners who require optimal conditions in order to hear 
and understand. Those who miss key words, phrases, and concepts because 
of poor listening conditions must struggle to keep up and may later do 
poorly academically and suffer from behavior problems. At particular 
risk are children who are experiencing temporary hearing loss from 
otitis media (as much as 15% of the school age population, according to 
a recent Centers for Disease Control analysis), children with mild to 
moderate permanent hearing losses, children with speech impairments, 
children who have learning disabilities and central auditory processing 
disorders, children for whom English is a second language, and very 
young children generally.
    Acoustical consultants confirmed that controlling the reverberation 
within a classroom and limiting the background noise generated both 
outside and within a space could provide significant improvement in 
speech transmission indices (STI) and signal-to-noise ratios (SNR) 
necessary for optimal performance of assistive technologies. Heating, 
ventilating, and air conditioning (HVAC) units and systems were 
identified as primary contributors to classroom noise. It was also 
noted that self-noise in classrooms can be dramatically reduced with 
reductions in reverberation time and background noise.
    Commenters familiar with school design and construction, including 
State education agencies, architects, and engineers, agreed that 
background noise and reverberation could be controlled using standard 
means and materials of construction. It was noted that new computer 
software makes it possible to quickly analyze listening conditions 
under a variety of design, construction, and finishing and equipment 
choices (basic acoustical design for classrooms

[[Page 60755]]

can also be accomplished with pencil-and-paper calculations). Many 
textbooks, manuals, and guides are available on architectural 
acoustics, and include values for the noise resistance of wall 
construction and the sound absorbency of common surfacing materials. 
Recommendations for limits on reverberation and background noise in 
classrooms have been included in architectural and engineering texts on 
acoustics for more than 40 years.
    Commenters pointed out that acoustical standards already exist in 
the model building codes, particularly for housing; in several State 
education and health department requirements for schools, in 
requirements for Federal courtroom design and construction, and in the 
building codes covering school construction in a number of European 
countries. HVAC equipment is commonly rated for noise output under a 
number of ANSI protocols, and the Los Angeles Unified School District 
has recently begun to require manufacturers and installers to observe 
noise thresholds on HVAC equipment placed in its schools. Two Fellows 
of the Acoustical Society of America (ASA) noted that the Society had 
formed a Working Group on Classroom Acoustics in 1997 under the ANSI 
Committee on Noise (S-12) and recommended that the Board pursue the 
joint development of a standard for classroom acoustics with the 
Working Group, which was preparing a draft standard for consideration.

Action

    Following a detailed analysis of the comments and research 
submitted in response to the RFI, the Access Board agrees that many 
classrooms are likely to include children for whom background noise 
must be controlled in order to optimize listening conditions. 
Furthermore, the Board has determined that collaboration with the 
existing ANSI/ASA Working Group on Classroom Acoustics would be the 
most effective way to develop technical and scoping recommendations for 
classroom acoustics. On March 10, 1999 the Board voted to support the 
efforts of the Working Group to draft a common standard for classroom 
acoustics that will incorporate criteria for children with 
disabilities. The ASA agreed to broaden the membership of the Working 
Group to involve other groups, including representatives of school 
systems, school designers, disability organizations, the U.S. 
Department of Education, and the Access Board and committed to a 2-year 
standards development process. The Access Board will fund some 
administrative costs of the Working Group and will consider additional 
funding, if necessary. After the standard has been ratified by the 
Committee on Noise, the Board will pursue its enforceability under the 
ADA or other statutes. This course of action is consistent with the 
Board's goal to take a leadership role in the development of codes and 
standards for accessibility and with the National Technology Transfer 
and Advancement Act of 1995, which requires Federal agencies to 
consider the use of private sector standards where appropriate.
    In May 1999, the Working Group was expanded with the addition of 
representatives of the Alexander Graham Bell Association for the Deaf 
and Hard of Hearing (AG Bell), Self Help for Hard of Hearing People 
(SHHH), the American Speech-Language-Hearing Association (ASHA), the 
American Federation of Teachers (AFT), The American Institute of 
Architects (AIA), the Council of Educational Facility Planners (CEFPI), 
the Educational Audiology Association (EAA), the American Academy of 
Audiology (AAA), the American Society of Heating, Refrigeration, and 
Air Conditioning Engineers (ASHRAE), and the American Society of 
Testing and Materials (ASTM). Other members may be added at the 
discretion of the Working Group co-chairs, the Access Board, and the 
U.S. Department of Education.
    Both the Access Board and the U.S. Department of Education will be 
active participants in the Working Group. In addition to the Acoustical 
Society of America (ASA), Working Group members from the acoustical 
professions represent the Institute of Noise Control Engineering (INCE) 
and the National Council of Acoustical Consultants (NCAC).
    The first meeting of the newly-expanded Working Group was held on 
May 18, 1999 in Fairfax, VA to consider a draft standard. The next 
meeting of the Working Group will take place on November 5-6, 1999 in 
Columbus, OH. Other meetings will be scheduled as required. All 
meetings will be open to the public. For further information, contact: 
Charles E. Schmid, Executive Director, Acoustical Society of America, 
365 Ericksen Avenue, Suite 324, Bainbridge Island, WA 98110, (206) 842-
6001, [email protected]. It is expected that a draft standard will be 
recommended to the Committee on Noise in Spring 2001 for balloting.
    Until a standard for classroom acoustics can be implemented, the 
Access Board offers the following technical assistance for the 
information of design professionals, schools, parents, and others who 
seek guidance on how to provide an acoustical environment that supports 
listening and learning.

Technical Assistance

    Many factors, including design and construction methods, teaching 
techniques, and amplification technologies, can affect the listening 
conditions in a classroom. Primary among them is background noise, of 
which there are several sources, some more amenable than others to 
treatment by design and construction means. Self-generated noise, for 
example, particularly in the lower grades, may be difficult to control. 
While a quiet room can minimize the need for raising the voice (and 
carpeting can soften the sound of footfalls and furniture), self-noise 
can be only partially ameliorated by architectural means. 
Reverberation--sounds that reflect from hard surfaces and arrive back 
at the listener's ear at different times--adds to background noise 
levels and smears the clarity of direct sound, thus reducing speech 
intelligibility. Fortunately, reverberation is relatively easy and 
economical to control--even in existing classrooms--by adding absorbent 
materials to certain room surfaces.

Speech Intelligibility

    Background noise both competes with and obscures the useful speech 
and other signals in a classroom. The greater the noise and 
reverberation in a room, the louder the signal must be to be heard and 
understood. Speech intelligibility is in part a function of the signal-
to-noise ratio (SNR). The SNR at a child's ear is the difference 
between the loudness of the signal (the teacher's voice, for example, 
typically about 60 dB) and the loudness of the competing noise in the 
room, from heating, ventilating, or air conditioning systems or other 
noise from within or outside the classroom (often measured in the 45-55 
dB range in classrooms). And because loudness varies with distance 
(every doubling of the distance between speaker and listener causes a 6 
dB drop in signal loudness), the SNR will vary as a child or teacher 
moves about the classroom.
    Decibel levels are usually measured at 3 feet from the speaker. 
When there are 6 feet--twice the distance--between speaker and 
listener, only 54 dB of the 60 dB delivered by the typical teacher 
reaches the student. At 12 feet, only 48 dB arrive. At 24 feet--the 
back row of a small classroom--only 42 dB will be audible. In some 
locations and at some times, the loudness of the background noise in a 
classroom may well exceed

[[Page 60756]]

the loudness of the desired sound signal. Research has shown that 
children who have temporary and permanent hearing loss need an SNR of 
at least +15--that is, 15 dB greater than the background noise--for 
adequate speech intelligibility.
    Children with other disabilities will also benefit from good 
classroom acoustics. In particular, children who receive speech 
therapy--the most frequently delivered special service in elementary 
schools `` need good listening conditions for themselves and their 
listeners. Research suggests that children who have auditory 
processing, language, and learning disabilities, particularly attention 
deficit disorders, find it easier to focus on an educational task if 
the SNR is higher. Audiologists have also called attention to children 
at risk because of age (young children just acquiring language 
generally need higher SNR values than adults) and native language 
(children for whom English is a second language have similar needs). 
Every student will learn more effectively in good listening conditions, 
but for children with hearing loss, including the often-undiagnosed 
temporary losses due to the common, chronic ear infections of 
childhood, good acoustics are an essential basis for learning and for 
other remediations necessary to learning.

Amplification

    Many children with hearing loss will use both personal (hearing 
aid) and classroom (radio frequency or FM) amplification to maximize 
SNR values. Amplification technologies can supplement the speech signal 
but cannot compensate for (or overcome) a poor acoustical environment. 
To be effective, amplification requires control of reverberation times 
and background noise. Furthermore, background noise, when amplified, 
can be painful and disruptive for children with a variety of auditory 
disabilities.
    Many schools are now installing soundfield systems--amplification 
distributed throughout the classroom--to improve listening conditions 
for all students, not just those who have hearing impairments. Note, 
however, that such amplification will add to background noise in work 
areas within the room and may impinge on adjacent spaces without 
adequate acoustical barriers in partition walls. In addition, most 
assistive listening and soundfield systems require that the speaker use 
a microphone, which may not always be feasible in group situations. 
Input from other speakers--aides, peers, and audio equipment, for 
instance--will not generally be amplified, and casual remarks may be 
missed. Educators recognize that the incidental learning that occurs in 
a classroom is as important to socialization, skill mastery, and self-
esteem as is the formal curriculum delivered by the teacher. And 
instructional methods are changing to small-group, computer-supported 
learning that makes it difficult to utilize these amplification 
technologies. By optimizing basic room acoustics, design professionals 
can ensure that all children have maximal access to teaching `signals', 
both directly and through assistive technologies.

Design Issues

    The characteristics of good architectural acoustics and the means 
to achieve good listening conditions in classrooms are well-known and 
not difficult or costly to apply in new construction and alterations. 
School architects who have had a standard education in HVAC and 
acoustical design may not even require the services of the acoustical 
consultant they would expect to include in a contract for the design of 
an audiovisual facility, auditorium, or concert hall. Facility and room 
acoustical design for good listening and learning environments will 
consider:
     Site, space, and classroom adjacencies that minimize 
classroom exposure to environmental, equipment, and occupancy noise;
     Room size and proportion for appropriate sound reflection 
and absorption;
     Slab, ceiling, roof, and wall construction (including 
doors and windows) that are appropriate barriers to noise;
     HVAC equipment selection, system design, and installation 
that minimizes structure, duct, and operating noise;
     Finishes selected and located for proper reverberation 
control, and
     Attention to electronic and radio-frequency interference 
with assistive devices.
    Good detailing, tight specifications, and careful construction and 
finishing will also be necessary to ensure that the facility and the 
spaces within it meet design intent. In general, the objectives of 
classroom acoustical design should be to control and limit background 
noise and reverberation.

Background Noise

    Noise can be mitigated at the source, along its path, and at the 
receiver. A combination of small improvements at each point can often 
produce the most cost-effective noise reduction. In general, favorable 
architectural acoustics will depend upon construction that resists the 
passage of sound, finishes that absorb sound energy, and HVAC design 
that minimizes noise output.
    The now-common practice of heating, cooling, and ventilating 
classrooms using through-the-wall or roof-mounted units has had a 
significant and deleterious effect on classroom acoustics. Few 
manufacturers have yet been motivated to control the noise of fans, 
compressors, and air movement through grilles that contributes the 
largest proportion of background noise in most existing classrooms. The 
research literature is replete with teacher reports of the need to turn 
off the heating or cooling unit during important lessons. Children with 
hearing loss must always be seated away from such noise sources and 
close to the teacher. While retrofit enclosures can achieve a reduction 
in noise output, it has been found to be a costly fix that few schools 
will fund. Ducted (and piped) systems with central HVAC equipment are 
much more suited to noise management through isolation and the 
manipulation of duct sizing, length, openings, and lining, but are 
often a casualty of cost-cutting. Unit ventilators are typically 
specified for hotel and motel guestroom construction where the 
background noise they contribute helps maintain acoustic privacy 
between rooms; as currently engineered, they are not appropriate for 
spaces in which communication is a primary function. What is most 
needed is a collaboration between schools, designers, and manufacturers 
to reduce the noise levels of such units, a re-engineering process that 
is being applied to many appliances and equipment.
    Background noise from the exterior environment can be managed with 
wall construction of appropriate sound resistance and the specification 
of multi-pane glazing and well-insulated and isolated frames typically 
required for energy conservation (sound reduction can be enhanced by 
pairing glass of different thicknesses). Windows and other openings are 
the weak link in building enclosure. Where exterior noise is 
significant, it will not be possible to maintain speech intelligibility 
in classrooms with the windows open.
    Background noise can also enter the classroom from adjacent 
spaces--other classrooms, the gymnasium, cafeteria, or auditorium, and 
corridors--through walls, doors, plumbing chases, and ducts. Sound-
resistant slab, wall, and ceiling construction and well-gasketed, 
sound-rated doors are the answer here. When designing building alarm 
systems,

[[Page 60757]]

it is a good idea to pair visible (strobe) and audible alarms in 
classrooms, since room enclosures with high Sound Transmission Class 
(STC) values may mute corridor bells.
    Noise generated within the classroom also contributes to background 
noise levels. Audio-visual equipment, computers, the pump in an 
aquarium, even lighting ballasts add decibels to the mix. The self-
noise of students working in small groups can be mitigated by 
increasing absorbent surfaces. Carpeting is used in many elementary 
schools to quiet the noise of footfalls and furniture shifting by 
younger children, who need higher SNRs for speech intelligibility. 
Recent advances in carpet technology have led to the availability of 
bacteria-resistant floor coverings.

Reverberation

    Reverberation is the measure of the time (in seconds) that it takes 
a given sound to decay by 60 decibels. Long reverberation times are not 
desirable because late-arriving sounds blur speech clarity and increase 
background noise. However, early sound reflections in rooms can 
actually reinforce the speech signal and improve SNR if they arrive at 
the listener's ear within 50 milliseconds. By placing materials to 
reflect early sound and absorb late-arriving noise, it is possible to 
optimize the reverberant characteristics of a given room.
    A recent paper by Rebecca Reich and John Bradley of the Canadian 
National Research Council reports on their investigation of classroom 
reverberation through computer modeling. Using the ODEON room acoustics 
ray tracing program (version 2.6 for DOS), researchers were able to 
identify optimum conditions for speech as a reverberation time of 0.5 
seconds (the research also showed that speech intelligibility varied 
only one-half of one percent between reverberations of 0.3 and 0.6 
seconds). Nine different placements of material, each with the same 
total of sound absorption, were tested. When the source position was 
located at the head of the room, in traditional classroom style, speech 
clarity was found to be optimal when the absorptive material was 
located on the upper portions of classroom side and rear walls.

Interference

    Interference from lighting ballasts, radio frequency sources, HVAC 
controls, and other electrical, electronic, microwave and even infrared 
sources can compromise the effectiveness of assistive technologies and 
has become an increasing problem for many people who are hard of 
hearing. Young children with hearing loss may not be able to identify 
and call attention to malfunctioning devices. In extreme cases, such as 
schools located in the path of transmission towers or equipment, it may 
be necessary to install shielding in exterior wall and roof assemblies.

Accessibility Recommendations

    In 1995, the American Speech-Language-Hearing Association (ASHA) 
published a Position Statement on Acoustics in Educational Settings 
that called for ``appropriate acoustical environments in all 
educational settings, to include classrooms, assembly areas, and 
communications-related treatment rooms''. ASHA's Acoustical Guidelines 
recommend that:
     Unoccupied classroom noise levels should not exceed 30 
dB(A) or a Noise Criteria (NC)-20 curve 2
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    \2\  NC curves weight sound pressure levels across 8 standard 
frequencies to approximate human perception of sound, which is 
greater in the high frequencies. To meet NC-20, sound pressure level 
at the lowest standard frequency (63 Hz) can be as much as 50 dB, 
while at the highest frequency (8000 Hz) it can be no more than 16 
dB).
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     Reverberation times should not exceed 0.4 seconds, and
     The SNR at a student's ear should exceed a minimum of +15.
    The ASHA recommendations are backed by substantial research and are 
the most authoritative on the subject of listening conditions for 
children who have hearing loss and other disabilities. An extensive 
bibliography is included. Self Help for Hard of Hearing People (SHHH), 
an advocacy organization, has endorsed the ASHA guidelines. AG Bell, an 
organization whose membership is over 50 percent parents of children 
with hearing loss and includes many professionals who work with 
children, advises its members to utilize the ASHA guidelines in 
advocating for an appropriate acoustical environment for children with 
hearing loss.

Industry Recommendations and Standards

    Industry coverage of acoustical issues rarely includes discussion 
of the characteristics of good listening conditions for people who are 
hard of hearing, although specialists in the design of facilities for 
people who are elderly have begun to recognize this as a significant 
issue. Acoustical design for children's environments is not typically 
distinguished from practices suitable for adults.
    Criteria for classroom listening conditions at three levels of 
quality were recently outlined in ``Goals and Criteria for Acoustical 
Planning'', a presentation by R. Kring Herbert, FASA, at the 1999 
conference ``Eliminating Acoustical Barriers to Learning in 
Classrooms'' in New York City, organized by the coalition formed to 
submit comment to the Board's RFI:

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                                         A-weighted
         Listening conditions            sound level         Room criteria (RC), Neutral 1             RT-60
                                            (dBA)                                                    (seconds)
----------------------------------------------------------------------------------------------------------------
Desirable (new construction).........              31  RC-25N                                                0.5
Adequate (alterations)...............              36  RC-30N                                                0.5
Poor.................................              41  RC-35N                                               0.5
----------------------------------------------------------------------------------------------------------------
1  Room criteria ratings were developed to assess the effect on listeners of HVAC noise, which can be annoyingly
  ``hissy'' (H) in the high frequencies and ``rumbly'' (R) in the low frequencies. Sound pressure levels for RC
  curves are lower at both extremes (46 dB maximum at 63 Hz and 13 dB maximum at 8000 Hz for RC-20) than NC
  curves, although they are identical at mid-range (26 dB at 500 Hz).

    Textbooks on acoustical design typically contain guidelines for 
maximum background noise in different occupancies. Recommendations in 
current publications show a range of 25 dB(A) to 35 dB(A) maximum for 
the interior sound level in unoccupied classrooms. Most texts do not 
distinguish between classrooms for children and classrooms for adults. 
Only Egan, of those consulted in the Board's analysis, considered hard-
of-hearing users. Egan recommends a 5 dB reduction in background noise 
for facilities serving people who have hearing loss. Reverberation 
times between 0.5 and 0.8 seconds have been recommended for classroom 
uses.

[[Page 60758]]

    The American Society of Heating, Refrigeration, and Air 
Conditioning Engineers (ASHRAE) in its 1995 Handbook suggests a Room 
Criteria maximum of RC-40N for small classrooms (<750 SF) and RC-35N 
for larger classrooms. This is considerably higher than most acoustical 
textbooks recommend, and recognizes no adjustment for classrooms for 
children or for people who have hearing loss.
    The American National Standards Institute (ANSI) in S12.2-1995, 
``Criteria for Evaluating Room Noise'' suggests RC-25-30 for lecture 
halls and classrooms and RC-35-40 for open plan facilities (where it is 
significantly more difficult to control background noise). Again, no 
adjustment is suggested for younger listeners or those who have hearing 
impairments.

Acoustical Modeling and Measurement

    Computer modeling is a useful way to project the effects of various 
design decisions and materials selections on the speech intelligibility 
of a classroom. Professional engineering software for acoustics 
analysis has been used for many years in the design of performance 
halls. New user-friendly software packages are now becoming available 
to assist non-specialists to determine reverberation time and specify 
proper locations and areas of absorbency.
    Both background noise and reverberation time can also be calculated 
from relatively simple equations contained (and explained) in most 
acoustics texts. Editions of M. David Egan's text ``Concepts in 
Architectural Acoustics'' has been a standard reference work for 
students of architecture since 1972. Tables of material and assembly 
characteristics needed for acoustics computations, including values for 
absorbency, sound transmission, impact isolation and other factors, are 
published in many textbooks; `Part IX Acoustics', in ``Mechanical and 
Electrical Equipment for Buildings'', by Stein, Reynolds, and 
McGuinness, has been an assigned text for architecture and engineering 
students through eight editions. Many manufacturers of acoustical 
finishes and products also provide details on wall, partition, slab, 
ceiling, and roof design in catalogs and product data sheets. 
``Architectural Graphic Standards'' and ``Timesavers Standards'', key 
resources for design professionals, both contain basic information on 
architectural acoustics and noise control, including design and 
construction details and noise reduction values.
    Background noise in existing facilities can be metered on several 
scales, including the A scale, which is adjusted for human hearing. 
Simple inexpensive devices may be adequate to determine the existence 
of an acoustical problem, but more sophisticated and costly devices are 
necessary to perform an acoustical analysis. Reverberation meters also 
exist, although they do not seem to be much used by consultants.

Standard-Setting and Regulation of the Acoustical Environment

    Acoustical standards are of two general types: performance 
standards, usually combined with a testing protocol, as with ANSI and 
ASTM standards, or design and construction standards that require a 
specified sound absorbency or sound transmission or resistance value in 
building elements--ceilings, walls, windows--known through prior 
testing to achieve certain results.
    Because design, construction, and use all affect the acoustics of a 
space, design professionals are understandably wary of single-number 
requirements for reverberation and background noise. A 5 dB difference 
in room performance could be due to meter quality, changes or omissions 
in construction, lack of equipment maintenance, teacher fatigue, or 
even a new flight pattern at a nearby airport.
    Sweden, Portugal, Germany, and Italy all have acoustical standards 
for educational facilities. The Swedish standard is based upon room 
area and absorbency values for ceiling tiles (the higher the absorbency 
rating of the material, the less area is required) and on the sound 
transmission class of wall, floor, and roof/ceiling assemblies. Italy's 
standard prohibits school construction where environmental noise 
exceeds certain levels (as, for example, near airports, rail lines, and 
highways). Research is underway in Great Britain to establish classroom 
standards for children who are hard-of-hearing.
    In the United States, the New York State Department of Education 
published a manual for classroom design and construction that sets 35 
dB(A) as a background noise `objective' for State school construction. 
Washington State Department of Health regulations also limit background 
sound to 35 dB(A) in classrooms. The Los Angeles Unified School 
District has attempted to limit noise from through-the-wall and rooftop 
HVAC units through their purchasing program, specifying a 35 dB maximum 
for equipment noise. The Access Board understands that the School 
District has not been able to identify a manufacturer of complying 
units. The District hopes that purchasing volume may encourage 
manufacturers to develop quieter models.
    The model codes (BOCA, UBC, SBC), several state departments of 
education or health, and the Department of Housing and Urban 
Development have already adopted acoustical standards for multifamily 
residential occupancies that establish minimum values for Sound 
Transmission Class (STC) and Impact Isolation Class (IIC) of wall and 
slab/roof assemblies. Multifamily housing in California is subject to 
design and construction standards for acoustical performance. 
Environmental (exterior) noise is also limited by regulation in many 
jurisdictions, and others require construction that will provide an 
interior noise level of no more than 45-55 dB.

Resources

    There are many other resources available for parents, schools, 
audiologists, advocates, and design professionals who wish to improve 
their understanding of issues in classroom acoustics. A coalition of 
organizations assembled in 1998 to respond to the Access Board's 
Request for Information (RFI) maintains a lively listserv and archive 
at [email protected] and contains links to other sites of 
interest. Professional members include the Acoustical Society of 
America, Alexander Graham Bell Association for the Deaf and Hard of 
Hearing (AG Bell), the American Academy of Audiology (AAA), the 
American Speech-Language-Hearing Association (ASHA), the Educational 
Audiology Association (EAA), the National Council of Acoustical 
Consultants (NCAC), Self Help for Hard of Hearing People (SHHH), and 
the Council of Educational Facility Planners, International (CEFPI). 
The U.S. Department of Education maintains a National Clearinghouse on 
Education Facilities. Its website on classroom facility design at 
http://edfacilities.org includes references to research and 
publications on classroom acoustics.
    Additional reading and reference material, including electronic 
links to other websites of interest, will be posted on the Access 
Board's website at http://www.access-board.gov/rules/acoustic3.htm.
June I. Kailes,
Chair, Architectural and Transportation Barriers Compliance Board.
[FR Doc. 99-28941 Filed 11-5-99; 8:45 am]
BILLING CODE 8150-01-P