[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:
thibault@access-board.gov.
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, charles@aip.org. 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)
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Desirable (new construction)......... 31 RC-25N 0.5
Adequate (alterations)............... 36 RC-30N 0.5
Poor................................. 41 RC-35N 0.5
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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="">classroomacoustics@onelist.com 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
