TECHNICAL
ACOUSTICAL
ISSUES TO BE CONSIDERED
IN NOISE REGULATION
Gary W. Siebein FASA, FAIA
Professor of Architecture
University of Florida
School of Architecture
gsiebein@siebeinacoustic.com
www.siebeinacoustic.com
Robert M. Lilkendey, INCE
Associate Principal
Siebein Associates, Inc.
Consultants in Architectural Acoustics
rlilkendey@siebeinacoustic.com
TECHNICAL ACOUSTICAL ISSUES TO BE CONSIDERED IN NOISE
REGULATION
prepared by
Gary W. Siebein FASA, FAIA
Professor of Architecture
University of Florida
School of Architecture
gsiebein@siebeinacoustic.com
www.siebeinacoustic.com
Robert M. Lilkendey, INCE
Associate Principal
Siebein Associates, Inc.
Consultants in Architectural Acoustics
rlilkendey@siebeinacoustic.com
ABSTRACT
The basis of noise regulation in communities is to maintain healthful,
productive environments for people to live, work, play, learn and prosper
together. Noise ordinances are usually developed to provide maximum
sound levels that can be emitted from one property or land use type to
another. The sound level limits are often prescribed using various
physical measurements of sounds using a sound level meter or some type
of qualitative assessment of the noise such as whether or not it is “plainly
audible,” “loud,” “raucous,” etc. This paper will review basic acoustical
terminology and concepts that attorneys and planners who regulate the
sonic environment should be aware of; the relationships between sound
measurements and the perception of loudness by people; the effects of
noise on human health and hearing as criteria for noise regulation;
standards from ANSI, ASTM and others that proscribe acoustical
measurement techniques; summarize general types of acoustical
regulations in noise ordinances used in various communities; and discuss
the applicability of the various types of ordinances for specific noise
issues in communities. Case studies will be presented for amplified
music entertainment noise; industrial noise; transportation noise of
various types; and mixed-use district noise issues. Additionally, an
emerging field of study called community soundscape design will be
discussed. Soundscape methods allow communities to not only regulate
excessive noise propagation after plans are executed and buildings are
built, but to consciously design for desirable acoustical qualities as they
grow, redevelop and emerge; and to aurally preview and discuss the
community soundscape with all involved stakeholders as one of the
considerations in the public planning process.
2
I.
INTRODUCTION
Le Corbusier, a famous architect who was one of the founders of the Modern Movement in
architecture, drew the sketch shown in figure 1. to illustrate the dual potential of sunlight to be an
absolute delight, on one hand, when it is brought into buildings to dramatically illuminate a piece of
sculpture or when shafts of daylight enter a beautiful cathedral creating a sense of spiritual space;
and on the other hand, to be a disaster when a large building is overheated in the summer creating
an unlivable space. The same sketch can, by analogy, relate to the propagation of sounds in a
community. What one person hears as music is viewed as intolerable noise by another. Therefore,
sound, like sunlight, can be a source of beauty when one hears an orchestra reach a dramatic
crescendo at the end of a Mahler symphony or when an actor on a stage speaks a soliloquy into the
silence of an awe struck audience. Sound can also be a source of great discomfort or annoyance
when deep, bass thumping sounds from a car stereo shake an entire line of traffic for a seemingly
unending period of time while stopped at a traffic light.
Figure 1. Sketch of the pain and pleasure of sunlight by Le Corbusier.
II.
HEALTH EFFECTS OF SOUND IN THE COMMUNITY
This is one of the reasons that communities develop noise regulations. There are often 4 standards
that are used as the acoustical rationale for noise ordinances. First are preventing sound levels that
cause hearing damage. The levels contained in the Occupational Safety and Health
Administration’s (OSHA) regulations are the usual levels cited. These are summarized in Table 1.
While hearing loss is well documented in the literature as one of the primary health effects
experienced by people exposed to noise in the work place, there is also a substantial body of
research that deals with identifying annoyance, speech interference and other less damaging effects
of noise related to hearing and comfort. The World Health Organization (WHO) has identified five
primary categories into which the effects of noise on people can be grouped.
1.
2.
3.
4.
5.
Temporary or permanent hearing impairment.
Interference with communication
Sleep disturbance
Temporary and permanent impact on the physiological functions of people
Social behavioral and annoyance effects.
3
A discussion of the physiological effects of noise should consider the
goal of maintaining a healthful environment for high quality living and
comfort. The presence of disease or illness is identified when an
irregularity of physiological functions is found to require treatment. This
is determined by comparing measured values of physiological indicators
to the mean and standard deviations of a “normal” population. If a
continuum is drawn from a diseased state requiring treatment to a low
quality of life standard to a high quality of life standard, the average for
the “normal” population with its standard deviation will overlap the
beginning of the standard deviation for the part of the population in
jeopardy. High quality acoustical environments where people do not
experience physiological or psychological symptoms and a relatively
high degree of acoustic comfort is noted to have an LAeq of 30-35 dBA
and Lmax of 45 dBA. Annoyance, sleep interference and other
psychological and physiological symptoms begin in the 55-65 dBA
range. People living in environments with an LAeq < 75 dBA are
considered to be in the highest extreme of a reasonably healthful
environment. Jeopardy for symptoms related to noise begins at 75 dBA.
Hearing loss occurs in environments with an LAeq > 85 dBA. Extra aural
overstrain occurs at Lmax > 99 dBA.
Table 1. Summary of OSHA noise levels and exposure time when hearing protection
devices are required in work places.
Duration Per Day, Hours
Sound Level dba Slow Response
8
90
6
92
4
95
3
97
2
100
1½
102
1
105
½
110
1/4 or
less
115
The second through fifth concerns are sound levels where health effects
other than hearing damage can occur. There is much debate about what
sound levels contribute to health effects. There is also an on-going
research effort to more clearly and definitively identify these sound
levels.
4
Figure 2. Diagram of the mean and standard deviations of healthy and diseased populations with corresponding sound
levels.
A.
Temporary or Permanent Hearing Loss
Working in high levels of noise gives rise to the possibility that people may suffer
noise induced hearing loss. There is a considerable variability in the human
sensitivity to noise and resulting hearing impairment. Damage risk criteria have been
developed to assess the probability that a noise-induced population will suffer
hearing losses. It is generally agreed that damage risk is negligible in environments
with 8 hour sound levels < 75 dBA. Thresholds published by the World Health
Organization are 70 dBA average sound levels over a 24-hour time period with
maximum sound levels < 110 dB for industrial and commercial activities for
5
continuous noise and a peak sound level of 140 dB
100mm from a person’s ear for impulsive sounds. In the
work place in the United States, OSHA, the Occupational
and Safety and Health Administration, has requirements
that a hearing conservation program be administered in
environments where the 8-hour sound level is > 85 dBA
and hearing protection devices be worn in environments >
90 dBA. OSHA also recommends that people be exposed
to impulsive sounds < 140 dB.
B.
Interference with Communication
There is a substantial body of literature that has explored
the ways in which verbal communication is hindered in
noisy environments. Metrics such as speech intelligibility
(SI) and speech interference levels (SIL) are among the
many indices that have been developed to relate how well
people can hear and understand words in the presence of
noise. Sound level limits recommended to one community
with a large and active entertainment district were
developed in part to allow measurable “just reliable
communication” among law enforcement officers in the
streets. Other effects of noise on communication include
fatigue as one attempts to listen for periods of time in the
presence of noise; concentration problems, decreased
work capacity and misunderstandings. Psychologically
these effects are sometimes manifest in a lack of self
confidence, irritation and uncertainty about what to do.
Maximum distances for “just-reliable” communication
with different voice levels can be estimated from metrics
in the literature (Handbook of Acoustical Measurements
and Noise Control, 3rd Edition by Cyril M. Harris and
Noise and Vibration Control, Revised Edition by Leo L.
Beranek). “Just reliable communication” is the ability for
people to just barely communicate with each other in
noisy situations.
The values in the table for A-weighted sound levels of 65
dBA and higher show that for effective communication
between officers, even when shouting, they can not be
across a roadway from each other. This means that if an
officer is trying to arrest someone causing a disturbance
and a fellow officer sees him about to be attacked from the
rear, shouts of warning can not be heard. This puts the
officer in a potentially life threatening situation. “Just
reliable” communication with raised and very loud voices
across a typical street can occur at sound levels of 55-65
dBA.
6
Table 2. Maximum distances for “just-reliable” communications at different noise levels (Harris, 1991, p.16.10).
NRC* = No Reliable Communication
C.
Sleep Disturbance
Noise from community noise sources such as outdoor amplified music,
transportation and industrial operations may impact residences where people are
sleeping. The World Health Organization recommends interior sound levels (Leq) of
30 dBA during nighttime hours. An Leq is the level of a steady sound that would
have the same A-weighted sound energy as a time varying sound over the same time
period. The Organization for Economic Cooperation provisionally recommends Leq
levels of 35 dBA for light sleep and 50 dBA for deep sleep. The European
Communities Commission recommends interior nighttime noise levels of 30-35 dBA
with maximum peak levels of 45 dBA to minimize sleep disturbance. Griefahn
found that the threshold for people awakening during the night was a peak noise
level of 60 dBA. Electroencephalogram or brain wave (EEG) readings begin to show
effects of peak noise levels as low as 37 dBA. It takes people 2-3 times longer to fall
asleep with peak noise levels > 60 dBA than in a continuous background noise of 40
dBA. People will wake up at peak sound levels of 60 dBA and will stay awake
longer once they awake as the noise level increases above 60 dBA. Heart rate
increases and vasoconstrictions occur at peak noise levels between 60 and 85 dBA.
Thresholds for physiological reaction to nighttime noise begin to occur at peak noise
levels of 50 dBA for children, 55 dBA for middle aged and older people and 60 dBA
for young adults.
7
Table 3. Summary of sound levels related to sleep disturbance and quality of life.
Agency or Author
Design Criteria
HUD, FAA
LDN < 45 dBA
ASHRAE
NC 25-35 (32-42 dBA)
WHO
Nighttime
Leq < 30 dBA
Organization for Economic Cooperative &
Development
Leq < 35 dBA Light Sleep
Leq < 50 dBA Deep Sleep
European Community Commission
Nightime Leq < 30-35 dBA
Lpeak < 45 dBA
Griefahn and Osada
Peak Levels <60 dBA
D.
Temporary and Permanent Impact on Physiological
Functions
There are three general types of physiological responses to
noise.
1. Adaptation. This usually occurs at low doses where
one may elect to close a window for example when
they hear unwanted noise.
2. Reversible damage which disappears when the noise
stops.
3. Non-reversible damage which usually results from
severe exposure and usually results in hearing loss.
The adaptive responses include muscle activities such as
startle responses and increased muscle tension in response
to the onset of sudden, high intensity sounds. These
effects diminish with repeated exposure to the noise
stimulus.
The evidence of epidemiological effects including change
of blood pressure, increase in cholesterol, appearance of
mental anxiety and depression at sound levels between 5075 dBA is not clear and somewhat ambiguous. The
evidence becomes much more clear at higher sound levels.
According to Jansen (1998) cardiovascular effects in
adults are the most visible of the physiological effects of
noise. These include changes in heart rate and reduction
in the diameter of blood vessels (vasoconstriction) in
peripheral regions (mostly the skin) and increases in blood
pressure. Respiration is accelerated and oxygen
consumption is increased in noise. There is a reduction in
salivation and intestinal action. Modifications of the
amount of secreted gastric juices and their composition
can lead to intestinal irritation and possibly stomach or
8
intestinal ulcers. Endocrine system effects are less visible
than cardiac, respiratory and digestive effects, but they are
the first responses to noise and cause other effects.
E.
Social, Behavioral and Annoyance Effects
Annoyance has been defined as a feeling of displeasure
with any agent or condition known or believed by an
individual or group to be adversely affecting them.
Exposure to noise has been shown to bring about changes
in mood, everyday behavior and other social indicators.
Among the negative emotions identified by people
exposed to noise are anger, disappointment,
dissatisfaction, withdrawal, helplessness, depression,
anxiety, distraction, agitation, and exhaustion. Annoyance
has been shown to be a complex response to the level,
duration, frequency (pitch), and time characteristics of
noise sources. It is also related to a number of nonacoustical issues as well such as the degree of control one
has over the noise source, the association one has with the
noise source and one’s previous experience with noise.
Glass and Singer (1975) found that exposure to
unpredictable and uncontrollable high intensity noise
often leads to degradation of the quality of tasks being
performed, impaired ability to resolve cognitive conflicts
and lowered tolerance for frustration. Geen and O’Neal
(1969) found that aggression increased to people exposed
to high level noise.
Cherek (1985) found that smoking increased as noise
levels increased in a laboratory study of noise exposure.
F.
Summary of Health Effects of Noise on People
Studies point to significant cardiovascular effects
including higher blood pressure and increased incidence
of hypertension in people exposed to high noise levels.
Stress reactions indicated by increased production of
hormones have also been clearly associated with noise
exposure. A variety of psychological effects of noise
including increased smoking, anger, depression, anxiety
and agitation have been observed. Working and/or living
in high noise environments brings with it decreased work
capacity, fatigue and misunderstandings as part of the
normal consequences of the difficult environment.
9
III.
GENERAL ISSUES TO BE CONSIDERED
DEVELOPING A NOISE ORDINANCE
IN
The goals of noise regulations should be determined with the full
participation of the community. Noise ordinances are often developed in
response to limiting the amount of noise that can be propagated across
real property lines. Therefore, the goal of the regulations is to define
what can not be done. There are few noise ordinances, comprehensive
plans or other regulations that attempt to define the positive qualities of
the sonic environment. In other words, few if any communities try to
define what sounds should be preserved, enhanced or deliberately
designed into their fabric. This is the subject of a relatively new field of
environmental acoustics called the soundscape or acoustic landscape.
Acoustical consultants, urban planners, community leaders, developers,
residents and other stakeholders can actually design, model and simulate
aural qualities of communities that are being developed. Statements of
sonic qualities that should be encouraged and/or enhanced can be made
in addition to those sounds that are necessary to limit.
A determination should be made involving all stakeholders in
participatory work shops of what types of noise are to be regulated. This
is especially important where a maximum sound level limit is contained
in the noise ordinance. There are some sounds that are necessary for the
normal life of the community that must be maintained while there are
other sounds that cause disturbances and are necessary to limit even
though they occur at the same level. For example, a rural community
may want to allow agricultural equipment such as harvesters, whose
noise can not be reduced in a practical manner, to operate without being
in violation of the law while they may desire to limit sounds at the same
level produced by noise from an industrial operation or teenager’s boom
box.
The acoustic landscape or soundscape varies with location in the
community. There may be some areas of a community where specific
noise sources are necessary to regulate while there maybe other areas
where the same noise sources or levels are not a concern. For example, in
redeveloping cities and new urbanist communities where mixed-use
zoning is encouraged, noise from outdoor amplified entertainment may
propagate into nearby by residences located above or next to the
entertainment establishment. In communities that segregate different land
uses, residential occupancies may be spatially separated from commercial
and entertainment venues and special acoustical provisions are not
necessary.
Sometimes multiple standards are used because one sound level limit for
any and all sources can not address all noise concerns. Therefore, several
standards may exist to attempt to deal with individual noise issues. For
example, many ordinances have separate provisions for air-conditioning
equipment noise when the equipment is operating properly.
10
Time duration of measurements-instantaneous, averaged, maximum,
percentile levels. The time duration and sampling of the data should be
determined based on the types of sound being measured. Most noise
ordinances require sound levels to be averaged over periods of time. The
time averaging tends to provide lower sound levels for acoustical events
that vary rapidly in loudness such as amplified music, gun shots, loud
impacts from loading dock activities and other short duration sounds.
Sound pressure level is defined as the instantaneous variations in
pressure attributed to the sounds. All sounds vary over time in loudness.
A concept sketch of a sound wave showing the difference between a
peak and average sound level is shown in figure 3.
An average sound level or an equivalent continuous sound level
averages the variations of sound pressure (not decibels) in periods of
time specified in the ordinance. The equivalent continuous sound level
or Leq is defined as the sound level that would result if a series of timevarying sounds occurred at a constant level for the same time period.
The Leq is less than the peak sound level which is defined as the peak or
short term maximum level reached by the sound wave sampled in a very
short time period. The Lmax or maximum sound level is the highest
sound level reached using the fast response on the sound level meter.
The Lmax is usually 10-15 dB less than the peak sound level for the
same acoustical event. The Lmax is often 3-10 dB higher than the Leq
for time varying sounds such as music. The Leq for a given sound will
usually decrease as the averaging time increases. Therefore, when Leq
acoustical measurements averaged over 5, 10, 30 or 60 minute time
periods are made, disturbing sounds are often difficult to distinguish
from ambient sounds and the complaints received by residents are not
substantiated by the measurement procedure selected.
Percentile sound levels are sound levels that are exceeded for
percentages of the measurement time. For example an L10 is the sound
level exceeded for 10 percent of the measurement time. Similarly L1,
L5, L50, L90 and L95 are the sound levels exceeded for 1%, 5%, 50%,
90% and 95% of the measurement period respectively. The L1 or L5 are
often used as approximations of the loudest sounds that occur during the
measurement period. The L50 is the sound level exceeded 50% of the
time. This metric is very not sensitive to time varying sounds. The L90
and L95 are thought to approximate the lower level sounds that occur in
a neighborhood.
Figure 3. Comparison of peak versus average sound levels
11
Standards and calibration. The American National Standards Institute
(ANSI) produces standards that are widely cited governing the design of
sound level meters, acoustical terminology, the design of the
measurement methods such as filtering, sampling, etc. and the operation
of microphones. The American Society for Testing Materials (ASTM)
publishes standards on measurement protocols including developing a
measurement plan, the use of specific sound measuring equipment,
metrics that can be used for different situations, the use of wind screens,
environmental conditions when measurements can occur, the
documentation of acoustical and environmental data pertinent to the
measurements and other factors that enforcement personnel and legal
staff should be aware of. General practice requires that meters are
calibrated in the field before and after each use to confirm accurate
performance. Meters and calibrators are usually sent to the factory when
problems arise and once every two years for calibration in current
practice with digital meters. Many older noise ordinances required yearly
calibration in the factory which was appropriate when analog meters
were used that were more electrically and mechanically volatile than
digital meters in current use.
Time constants and sampling rates. Sound level meters can be set with
different time constants and sampling rates. A slow response on a sound
level meter “weights” the response of the meter to one second. A fast
response on the meter “weights” the response to 1/8 second. The fast
response meter can capture events that vary rapidly in time more
accurately than a slow response. Sounds that occur in very short time
periods such as the metal clanging of a dumpster being emptied, a
gunshot, or a ramp clanging on a loading dock floor are best measured by
their peak or maximum value. Many sound level meters have peak
detectors that allow the true peak of the sound wave to be recorded.
Digital sound level meters can sample up to 44,100 times per second.
This is basically the same sampling rate at which compact discs and
digital video discs are recorded. This allows the most accurate
representation of time varying signals. It also allows the data to be played
back as .wav files so the actual sounds recorded can be “heard” as they
were measured as opposed to just being represented by a number. This
likely represents the way of data recording and analysis in the future.
Corrections for background or ambient noise. All noise disturbances
occur in the presence of a background or an ambient sound level.
According to ANSI standards, the ambient, background and residual
sound levels are three distinct quantities. The ambient sound level is the
combination of all sounds including the source of interest at a particular
location. The background sound level is the sound level attributed to all
sources at a location except the source of interest. The residual sound
level is the sound level remaining after all identifiable sound sources
have been identified and removed or subtracted from the measurement.
In other words, there may be cars passing on a road while a measurement
of a disturbing noise is being made. ASTM standards require that
mathematical corrections be made to account for the contribution of the
background sounds to the measurement. This is done by one of three
12
methods. If possible, a measurement of just the background sound is
made. Immediately after or before, a measurement of the combined
background sound and disturbing sound is made. The second method is
to take measurements of the background noise in moments of “quiet”
between times when the disturbing sound is being made. The third
method is to take average background sound levels in different districts
of a community that are applied to the source sound if needed.
If the background sound levels are 10 dB or less than the disturbing
sound, no corrections are required. The corrections can be made by use
of a table or graph of values based on the difference between the
background sound level and the disturbing sound level or by use of a
computer algorithm to make the corrections automatically as part of the
data analysis process.
Data acquisition, storage and presentation. Digital sound level meters can
log data over the measurement period, store it to internal memory and
allow it to be saved, retrieved and graphed at a later time. Analog sound
level meters require the operator to manually write down the
measurement results on a piece of paper. The decision as to which type
of meter to use is largely determined by the level of sophistication,
training and comfort enforcement personnel have with using sound level
meters and computer software. Hand writing data that is varying
instantaneously is a difficult task for someone to undertake especially
when a number of spectators (usually the complaining parties) may be
present. Most sound level meters will either have an analog needle that
moves across a numerical dial on the face of the meter or a digital screen
where constantly varying sound levels are flashed on the screen once or
twice per second. An officer must record the values of some type of
“eyeballed” average of the values on a sheet that may ultimately be
entered as evidence in a court proceeding. On the other hand, the time it
takes for one to become familiar with a complicated technical instrument
as well as data analysis software especially when it is infrequently used
may also be a difficult task. However, the digital meter provides a time
and date stamp with the data as well as a permanent record of the sound
levels that were measured that can be printed or graphed on a computer,
and may stand up better in court.
Accuracy of the sound level meter. There are two basic types of sound
level meters that are usually used for community noise enforcement. A
Type 2 meter has an accuracy of ±1.5 dB and is useful for general
enforcement of non-critical cases. The 3 dB tolerance of a type 2 meter
means that essentially 50% of the sound energy may not be accounted for
in the measurement. A Type 1 sound level meter has an accuracy of ±1.0.
dB. This is also called a precision sound level meter. This is the type of
meter that is most widely used by acoustical consultants.
Character of sounds - tones, impulse or impacts. Noise ordinances often
include “penalties” for sounds that do not have uniform time and pitch
characteristics. A tone is a sound with frequency components or pitch
that stand out relative to the other adjacent frequency components of the
13
sound. A back-up beeper on a tractor is an example of a sound with a
strong tonal characteristic that makes it very audible to people. Large
fans, mufflers on motorcycles and certain types of music all have
characteristic tonal components that make them more noticeable at lower
levels than continuous, broad band sounds. Impulses are short duration
sounds that rise to a very high peak and then rapidly fall to lower levels.
Gun shots are examples of impulsive sounds. Impact sounds are sounds
that result from the impact of two hard objects or of one object on
another. Footsteps on hard surface floors, hammers striking nails or
ramps clanging on a loading dock are examples of impact sounds. These
sounds tend to be more noticeable and more annoying than continuous
sounds such as water flowing because of the rapid rise of the sound from
relative quiet.
Enforcement personnel. Law enforcement officials and building officials
are the two predominant sources of enforcement personnel in most
communities for noise ordinances. The advantage of using law
enforcement personnel is that they are already on the municipal payroll.
Many communities have a relatively small number of noise complaints.
The officers can respond to these complaints at all hours of the day and
night as part of their normal duties. This has the disadvantage that many
law enforcement officers or building officials do not have specialized
training in noise measurement and environmental noise. They are
sometimes unsure of applicable standards and are not confident in their
data acquisition and interpretation of the data. Sometimes specialty
consultants are engaged by local governments to take acoustical
measurements and respond to citizen complaints.
Training and equipment used for enforcement. The level of training,
experience and day-to-day activities spent by enforcement personnel
involved with noise measurement is essential to build defensable cases.
Sound level meters that are relatively simple to use, but sophisticated in
operation can be purchased. Effective enforcement will demand on-going
training and experience by more than 1 officer in most cases.
“Undercover” acoustic enforcement. In many areas, potential violators
such as night clubs, people with car sound systems and others may
violate the law and/or cause complaints. When a uniformed officer
arrives and points a sound level meter at the source, a mute switch or
volume control can be quickly activated and evidence to support a
citation is effectively destroyed. It is possible to use equipment that can
be concealed in normal clothing to make enforcement actions less visible
if desired.
Special permits. There are some events that may contribute to the social,
economic, religious or cultural climate of the community that residents
and businesses may desire to allow periodically. These may include
special festivals, concerts, sporting events and other activities that can
not meet noise regulations so exceptions are granted often times on a
permit basis.
14
Link noise ordinance requirements with planning and zoning requirements for new and proposed
projects. Most noise ordinances are written on a complaint driven basis. In other words, citizens
call an enforcement agency when they perceive that a violation occurs. The enforcement agency
investigates and determines if a citation is warranted. This occurs after a building designed to
conduct a noisy activity has been built and occupied. It is possible to conduct acoustical analysis of
proposed projects to determine if noise mitigation design will be required before a project is
actually constructed. Therefore, requiring a noise impact study for prospective projects as part of
the planning process provides developers or building owners with knowledge before construction
that a noise violation may occur and allows them to design methods to reduce noise propagation
into the community during construction.
Link noise ordinance compliance and noise impacts with building permits and Certificates of
Occupancy (C.O.) for new buildings. It is also possible to require an acoustical verification test
prior to issuing a C.O. so the community is protected from potential noise sources. Post occupancy
noise impact studies can also be conducted by qualified consultants to verify conformance for new
projects with noise ordinance provisions or otherwise enforcement will only occur through a
complaint process.
IV.
ACOUSTICAL TOPOLOGIES OF NOISE ORDINANCES SURVEY RESULTS
A sample of 35 noise ordinances were reviewed from cities, towns and counties across the United
States as well as the World Health Organization community sound level recommendations to
establish a database for our office to work from in providing acoustical recommendations to
communities regarding noise ordinance requirements. The types of ordinances; overall and octave
band sound level limits found in the ordinances; plainly audible measurements found in the
ordinances; the location of measurements required in the ordinances; restrictions on commercial
music or amplified music found in the ordinances; other special provisions of the ordinances; and a
discussion of the major points relative to developing a noise ordinance are presented in the sections
below.
A
Overall Sound Level Limit Ordinances
A noise ordinance that limits the propagation of sound from one property to
another based on the measurement of the overall sound level at the source or
receiving property is called an Overall Sound Level Limit Ordinance. There are two
basic types of Overall Sound Level Limit Ordinances: one that is based on the
overall A-weighted sound level and one that is based on the overall C-weighted
sound level. Two thirds (67%) of the noise ordinances reviewed had an overall
sound level limit. Only 6 of the 35 ordinances (16%) had the overall sound level
limit as the only means to limit noise.
There are also subtle differences among noise ordinances with quantitative sound
level limits as to the duration of the measurement, whether it is a short term
sample or a longer term level or an equivalent continuous sound level, etc. A
review of these details is not included in this document.
Overall A-weighted sound level limits. The most typical type of noise ordinance is
one that limits the propagation of sound from one property to another by specifying
A-weighted sound level limits that can not be exceeded. This type of ordinance
usually has lower limits at residential property lines than at commercial property
15
lines. It also has lower limits for nighttime hours than for daytime hours.
An A-weighted sound level is one to which an A-weighting filter has been applied.
The A-weighting filter approximates the response of the human ear to lower and
medium level pure tone sounds. It deducts significant amounts of sound energy from
the low frequencies. This presents a problem with regard to equipment noise and
bass musical sounds because the bass or lower frequency sounds are decreased by
substantial amounts when using the A-weighting measurement process. This means,
for example, that ambient noise on the street or in a residence on the A-scale may be
measured as just about the same sound level with and without disturbing levels of
bass music being played. The bass music is easily heard by people listening, but it is
not recorded by an A-weighted sound level measurement. Not quite two thirds of the
noise ordinances reviewed (24 of 35 or 68%) had an overall A-weighted sound level
limit. Only 14% (5 of 35) had an overall A-weighted sound level as the only method
of limiting noise.
10
Flat
0
C-Weighted
-10
-20
A-Weighted
-30
-40
-50
31.5 Hz
63 Hz
125 Hz
250 Hz
500 Hz
1000 Hz
2000 Hz
4000 Hz
8000 Hz
1/3 Oc tave Band Center Frequenc y (Hz)
Flat
C-Weighted
A-Weighted
Figure 4. Comparison of A-weighted, C-weighted and Flat weighted Sound Spectra.
Figure 5. Comparison of A-weighted and C-weighted Sound Levels at a restaurant.
16
Overall C-weighted sound level limits. A C-weighted sound is one to which a C
filter has been applied. Very small amounts are subtracted from the low frequencies
and the high frequencies in an attempt to simulate the response of the human ear to
fairly loud sounds.
Only one ordinance was found in our sample of 35 ordinances that specified overall
C-weighted sound level limits. Interestingly, this ordinance was enacted in response
to the advice of a consultant as a way to account for the low frequency sounds found
in deep, bass music. The ordinance was recently repealed in favor of a “plainly
audible” ordinance due to difficulties measuring the disturbing music relative to
the ambient noise.
B.
Octave Band Sound Level Limits
Some noise ordinances adopt octave band or one-third octave band sound level
limits to define a disturbing noise. An octave band is a group of frequencies where
the highest frequency is twice the lowest frequency. For example, the octave band
centered at 250 Hz, which is approximately middle C on a piano, would extend
from 177 Hz to 355 Hz. A one-third octave band is a group of frequencies that is
only one third of an octave wide. The one-third octave band centered at 250 Hz
would extend from 224 Hz to 282 Hz.
All of the ordinances in our sample (20% or 7 of 35) that had octave band sound
level limits also had overall A-weighted sound level limits. All but one of these
ordinances also had “plainly audible” language as well, particularly for amplified
musical sounds.
Octave band or one-third octave band sound level limits provide the most precise
way to measure the disturbing sounds using typical equipment of modest cost. It is
possible to present graphs, as included in this document showing several sounds
compared to the ambient in a way that demonstrates why sounds with similar
overall levels can be heard as disturbing due to differences in the frequency content
or pitch of the sounds. In other words, why the bass sounds heard at a private
residence shown in figure 3 which were only 1 dBA above the ambient, but
actually have 10-15 dB more energy in the low frequencies might be
disturbing. This level of quantitative discrimination requires highly trained
personnel to record and interpret the results of the measurements. However, it
does provide suitable documentation for enforcement. The octave band or onethird octave band measures also provide enough information to a consultant to
prescribe remedial measures to reduce the propagated sound.
C.
Maximum Sound Level Relative To The Ambient
Four (4) of the ordinances (10% of the sample) contained provisions to limit the
maximum sound level to 5 dBA above the ambient level while one ordinance
limited the maximum sound level to 10 dBA above the ambient. Several of
these ordinances provided a table of ambient noise levels for different districts
within the community in case an enforcement officer could not make a reasonable
measurement of the ambient noise level at the time and place of the complaint.
Several of these ordinances also had tables of octave band sound levels in case one
had to make octave band measures to capture the disturbing sound.
17
These ordinances recognize that as the sound level decreases in a community during the
night, people will be disturbed by sounds that might not be annoying during daytime
hours. The disadvantages of a maximum sound relative to the ambient are listed below.
1. It requires two measurements to be made: one of the disturbing sound and one of the
ambient sound.
2. It requires a comparison to be made between the two measures at the site of the
violation.
The advantages of this method are listed below.
1. It provides a sliding reference scale that accurately represents the relative sounds of
the environment in which a disturbing sound is made.
2. It relates to the magnitude of the disturbing sound above the ambient at the time and
place of the complaint. Therefore it is an accurate representation of the quantitative
difference heard by the people in the vicinity.
This type of ordinance is often most effective if it is measured on an octave band or onethird octave band basis.
D.
Plainly Audible Ordinances
The second most typical form of noise ordinance is one that limits the propagation of
sound to levels that are plainly audible to a person of normal sensibilities at a certain
distance from the sound source or at the property line of the receiver. Sixty percent (21
of 35) of the noise ordinances surveyed included plainly audible provisions. Twenty two
percent (8 of 35) had the plainly audible provision as the only method of limiting noise
with no provisions for quantitative sound level limits. These noise ordinances are
especially used for amplified sound and other sounds that are difficult to measure, but
which are often the source of complaints within communities.
Many communities enact “plainly audible” noise ordinance requirements particularly for
amplified music because of the inherent difficulties in measuring short duration, bass,
thumping sounds by enforcement personnel who are not trained acoustical consultants
and who have sound level meters that only measure overall A-weighted and C-weighted
sound levels. The experience of many enforcement personnel is that people will hear
sounds that are disturbing, particularly at night, and file a complaint or call the police.
When an officer arrives and measures the sounds with an overall A-weighted sound
level meter, cars passing on the street, people talking and even insects may create louder
levels than the sounds upon which the complaints are based, particularly if they are bass
sounds. Furthermore, the overall A-weighted sound levels can be very low, yet still
have enough bass sound to be very disturbing.
E.
Nuisance Ordinances
Some communities enact nuisance ordinances that prohibit sound levels deemed to be
“loud, raucous, or otherwise disturbing the peace, quiet, repose,” etc. of the community.
Approximately one-third (37% or 13 of 35) of the noise ordinances surveyed included a
provision for declaring excessive sound as a public nuisance. Only one of the ordinances
18
had the nuisance provision as the only method of limiting noise. The enforcement of
these ordinances is based on a qualitative assessment of the nature of the sound.
F.
Multi-Tiered Or Multiple Method Noise Ordinances
A popular form of noise ordinance found in our sample was a multi-tiered or multiple
method noise ordinance. A multi-tiered or multiple method noise ordinance typically
had a combination of plainly audible language with A-weighted sound level limits as
well as a series of specific prohibitions. This provides flexibility in the enforcement of
the ordinance by allowing simple cases to be cited with the use of an A-weighted level,
amplified music to be limited by the plainly audible requirement, and other cases to be
cited based on more detailed octave band levels. Approximately 18% of the ordinances
(7 of 35) had both overall A-weighted sound level limits and octave band limits.
Approximately one-third (13 of 35) of the ordinances had overall A-weighted sound
level limits and plainly audible provisions. Approximately 13% (5 of 35) had overall Aweighted sound level limits and octave band limits and plainly audible provisions.
Seventy percent (26 of 35) of the ordinances surveyed had more than one method to
limit sound. Twenty nine percent (11 of 35) had more than two methods to limit sound.
Generally, in a multiple method ordinance, there is language stating that the most
stringent requirements prevail.
Location of Measurement. The ordinances in our sample were split between
measurement at the receiving property (approximately 75% of the ordinances) and
measurement at the source property (approximately 25% of the ordinances).
The advantages of using the source property line as the point of enforcement are listed
below.
1. The complainant does not have to be identified.
2. Law enforcement personnel do not have to enter a private property or residence to
enforce the ordinance.
3. Club owners and others can self-regulate sounds made at their establishments by
measuring sound levels immediately outside their place of business.
The disadvantages of using the source property line as the measurement location are
listed below.
1. The sounds measured are only loosely correlated with those heard by residents.
2. Clubs can reduce the sound levels of amplified music systems as they see
enforcement officials approaching.
3. Unusual sound propagation paths such as sounds reflecting off a lake or large
building are not taken into account which may exist between the source and
particular residences.
4. The effects of low frequency bass energy being amplified by resonating the building
structure of the receiver are not taken into account. Sound levels are often found to
be higher inside the homes than they were outside due to resonating walls, roofs etc.
within the home when low frequency noise is the disturbing sound.
5. The complainant does not have to be identified.
19
G.
Specific Exceptions To The Noise Ordinances
The following items were excluded from at least one of the noise ordinances reviewed.
The number on the right indicates the number of ordinances reviewed from which it was
excluded.
Cars on a public right-of-way
4
Parks and playgrounds
1
Trucks on a public right-of-way
4
Church bells or chimes
3
Aircraft
4
Licensed game hunting
1
Motorboats
1
Target shooting
1
Emergency warnings
6
Sound from commercial use
1
Emergency work
6
Sounds from industrial use
1
Fire alarms or burglar alarms
2
Sounds from professional use
1
Construction noise
4
Sounds from business use
1
Lawn care & mowing
4
Soil cultivation
2
Tree maintenance
3
Refuse collection (daytime only)
2
Power tools (daytime only)
3
Tractors
1
Street sweepers
1
Mosquito foggers
1
Lowing of cattle
1
Clucking of fowl
1
Neighing of horses
1
Baying of hounds
1
Sound of reasonable cared for domestic
animals
1
Unamplified human voice
4
Cultural, sporting, ceremonial or traditional
6
Performances at a public amphitheater
1
Performances at an outdoor park
1
Non-commercial public speakers
1
20
H.
Specific Prohibitions In The Noise Ordinance
The following items were specifically prohibited by at
least one of the noise ordinances reviewed. The number on the
right indicates the number of ordinances reviewed in which it
was prohibited.
Steam engines, internal combustion engines, etc. without silencers
1
Motorcycles, motorboats, motorboats without mufflers
1
Motor vehicles not traveling on a public right-of-way
1
Out of repair motor vehicles
1
Car horns or other devices not signaling an emergency
4
Places of entertainment outside or partially enclosed
3
Loudspeakers or public address systems or amplified music (when
“plainly audible”)
4
Radios, televisions, etc. (“plainly audible” or causing a disturbance
4
Receiver sets, musical instruments, etc. (when plainly audible or >
65 dBC at night)
2
Radios in cars (when “plainly audible)
3
Radios in shopping malls, streets, etc (audible to others)
1
Outdoor entertainment areas (when plainly audible)
1
Animals or birds (howls, barking, meows, squaks, etc) that create a
disturbance particularly at nighttime
5
Construction or demolition that causes a disturbance at night
3
Loading or unloading (including garbage) at night
2
Private emergency signaling devices (alarm, siren, whistle, etc)
3
Power tools or lawn mowers at night
2
Pumps, air-conditioners and other equipment that causes a
disturbance
3
Loud noises at a hospital or other “sound sensitive zone”
3
Shouting or crying of peddlers, etc. street sales, “whooping of
anyone”
6
Steam, compressed air whistles, etc.
1
Bottling plants, dairies, factories, machine shops, etc. at night
1
21
Limits on Interior Sound Levels in Places of Entertainment. Several of the
ordinances contained provisions to set maximum limits of the noise exposure
patrons of clubs can be exposed to by limiting maximum sound levels inside the
clubs. Los Angeles limited the sound level inside clubs to 95 dBA. Gainesville,
Florida limited the sound levels inside clubs to the OSHA limits. The City of Tampa
limited the sound level to 85 dBA inside clubs. New York City prescribed 45 dBA
in adjacent buildings as a way to limit sound produced inside a club.
I.
Special Provisions In The Noise Ordinances Reviewed
Many of the ordinances surveyed included special provisions to clarify the
measurement of sound. Some of the provisions are as follows.
Nighttime Hours Defined. Nighttime hours were defined for different time periods
in the ordinances studied. The range was from 6 pm to 2 am. Most of the ordinances
used 10 pm or 11 pm as the beginning of the nighttime period.
Distance Requirements. Several of the ordinances had provisions to limit the playing
of outdoor or indoor commercial amplified music at distances varying from 100 ft to
500 ft away from residential areas.
Plainly Audible Clarified. Plainly audible provisions often had a distance associated
with them. The distances varied from 0 ft (in other words at the source) to 300 feet.
Distances of 50 feet were the most common. Definitions of plainly audible from the
ordinances varied somewhat from ordinance to ordinance. For example, the City of
Gainesville, Florida has considerable text describing a process to “measure” plainly
audible sound using the ears of the enforcing officer. It is essential to word this type
of ordinance carefully so it will withstand challenge in legal proceedings.
Four (4) of the ordinances (including San Francisco, Los Angeles and Plantation,
Florida) had extensive lists of qualitative criteria that could be used to declare a
sound as unnecessary or illegal in the absence of sound level measurements.
Unenclosed Places of Public Entertainment Defined. Several of the ordinances
defined unenclosed places of public entertainment or otherwise limited the playing
of amplified music outdoors. For example, the City of Gainesville provided the most
extensive definition of unenclosed places of public entertainment by stating that it
had a sound transmission loss from inside to outside of less than 20 dB.
Provide Sound Insulation in Homes and Businesses. Both the City of Gainesville
and Miami Beach had provisions to allow the City Manager or other official to
request upgrading of homes or business properties to prevent either excessive
propagation of sounds from businesses and/or excessive complaints from residents
living or working in places that allowed too much sound to enter or leave the
building.
22
REFERENCES
Beranek, Leo L. Noise and Vibration Control, Revised Edition. John Wiley & Sons, November:
2005.
Bronzaft, Arline L. The Effects of Noise on Learning, Cognitive Development, and Social Behavior
in Fay, Thomas H., ed. Noise and Health. New York Academy of Medicine, New York: 1991.
Cowan, James P. Handbook of Environmental Acoustics. John Wiley & Son, 1994.
Harris, Cyril M., ed. Handbook of Acoustical Measurements and Noise Control Fourth Edition,
Institute of Noise Control Engineers, Poughkeepsie, New York: 2001.
Jansen, Gerd. Physiological Effects of Noise in Harris, Cyril M., ed. Handbook of Acoustical
Measurements and Noise Control Fourth Edition, Institute of Noise Control Engineers,
Poughkeepsie, New York: 2001.
Raymond, Lawrence W. Neuroendocrine, Immunologic and Gastrointestinal Effects of Noise in
Fay, Thomas H., ed. Noise and Health. New York Academy of Medicine, New York: 1991.
Schwela, Dietrich H. World Health Organization Guidelines for Community Noise. Noise Control
Engineering Journal, Vol. 49, No. 4, July-August 2001, pp. 193-198.
Sloan, Richard P. Cardiovascular Effects of Noise in Fay, Thomas H., ed. Noise and Health. New
York Academy of Medicine, New York: 1991.
Vallet, M. Effects of Noise on Health in Garcia, A., ed. Environmental Urban Noise. WIT Press,
Southampton: 2001.
23
APPENDIX A
Summary of Requirements of Noise Ordinances Reviewed
Table Summary of Requirements of Noise Ordinances Reviewed
No.
City
State
Day
time
dBA
Night
time
dBA
1
Alachua
County
Florida
60
55-Int. noise
within MF
Unit
55
45-Int.
noise
within MF
Unit
2
Boston
Massachusetts
70
50
3
Bradenton
Florida
60 res
65 comm
75 indust
55 res
60 comm
75 indust
4
Charleston
South Carolina
dBC
Octave
band
levels
Plainly
Audible
at 100'
Other
provisions
No person shall make or
cause to be made any
unreasonable or excessive
nosie that disturbs peace
Playing outdoor amplified
music between hours of
11:00pm to 7:00 am
prohibited
Excessive noise serious
hazard to public health,
welfare, peace, safety and
quality of life
5
Charlotte
North Carolina
55
50
7
Denver
Colorado
55
65-Comm
50
60-Comm
8
Gainesville
Florida
61 res
66 comm
55 res
60 comm
9
Hillsborough
County
Florida
60 res
65 comm
75 ind
55 res
60 comm
75 ind
Measured at distance of
200 feet from the real
property line of source
yes
Sound levels generated by
entertainment or musical
events with the Ybor City
Historic District, regardless
of time of day shall not
exceed 65 dBA when
recieved at any point south
of the right of way of the
CSX rail line along 6th
Avenue, east of 22nd
Street, north of Palm
Avenuem or west of
Nuccio Parkway
Disturb the peace
60 dBA at any point on
neighboring property line
55 dBA at center of
neighboring patio
55 dBA outside the
window nearest the source
10
Houston
Texas
65
58
11
Hudson
New
Hampshire
55
65-Comm
75-Ind
50
65-Comm
75-Ind
SA
“
Siebein Associates, Inc.
Amplified sound unlawful if
disturbs the peace
Appendix A-2
No.
City
State
Day
time
dBA
Night
time
dBA
dBC
Octave
band
levels
Plainly
Audible
12
Indianopolis
Indiana
13
Jacksonville
Florida
55 res
60 comm
55 res
60 comm
14
Key West
Florida
75 res
75-comm
60 res
75-comm
Sunset Celebration at
Malory Square exempt
15
Larimer
County
Colorado
55
25 ft from
source
50
25 ft from
source
During the hours of 7:00 am
to 7:00 pm noise may be
increased by 10 dbA for a
period not to exceed 15
minutes in any one hour
period
16
Lee County
Florida
66 res
72 comm
55 res
65 comm
17
Los Angeles
California
50 res
60 comm
65 indust
70 heavy
indust
40 res
55 comm
65 indust
70 heavy
indust
19
Malibu
California
20
Manatee
County
Florida
55 res
75
indust
50 res
75 indust
21
Marion
County
Florida
55 noise sens
65 res
65 comm
75 indust
55 noise
sens
55 res
60 comm
75 indust
22
New Jersey
State Model
Noise
Ordinance
New Jersey
65
65-Comm
50
65-Comm
yes
23
New York
City
New York
55
45
45 dB in
any 1/3
octave
band
63-200
Hz
24
Orange
County
Florida
55 noise sens
60 res
55 noise
sens
55 res
yes
25
Orlando
Florida
60 res
70 comm
75 indust
55 res
65 comm
75 indust
Exemptions for downtown
entertainment district 5:50
pm to 2:00 am
26
Panama City
Florida
60
55
Loud, racous, cannot
interfere with comfort
SA
“
50 ft at
night
Other
provisions
Creation of loud,
unnecessary or unusual
noises of various kinds
constitute public nuisance
yes
at 50 ft
limits
based on
dB of NC
curves
at 150 ft
disturb the peace, quiet, and
comfort
> 5 dB above ambient noise
in any adjoining unit
95 dBA limit in places of
public entertainment (without
sign)
Unnecessary noises, sounds,
or vibrations which are
physically annoying to
reasonable persons
Siebein Associates, Inc.
Vibration displacement limits
yes
45 dBA inside any home
produced by music noise
quality zones
Appendix A-3
No.
City
State
Day
time
dBA
Night
time
dBA
dBC
Octave
band
levels
Plainly
Audible
Other
provisions
27
Pittsburgh
Pennsylvania
68
68
Measured at or adjusted to a
distance of 75' beyond the
boundary of the property in
which the audio amplification
or reproduction system is
located
27
Plantation
Florida
55 single- fam
residence
60 multi-fam
residence
65 comm
70 indust
50 singlefam
residence
55 multifam
residence
65 comm
70 indust
50 dBA day, 45 dBA night
limit on sound levels in
sleeping or living rooms of
any dwelling
Limits for maximum sound
levels and pure tone
AC noise 60 dBA at any point on
neighboring property line
55 dBA at center of
neighboring patio
55 dBA outside the window
nearest the source
28
Portland
Oregon
55
60-Comm
65-Ind
50
55-Comm
60-Ind
30
San Francisco
California
55
50
31
Sarasota
County
Florida
32
St. Petersburg
Florida
L50 levels
75 res
75 comm
L50 levels
60 res
70 comm
33
Tampa
Florida
85 - Central
Business
District, Ybor
City Historic
District, and
Channel
District
60 - All other
areas
65 Central
Business
District,
Ybor City
Historic
District,
and
Channel
District
55 - All
other areas
yes
>5 dBA above ambient
Qualitative criteria to define
disturbance
annoy disturb, injure, or
endanger the comfort, repose,
health, peace or safety
yes
yes
AC noise 60 dBA at any point on
neighboring property line
55 dBA at center of
neighboring patio
55 dBA outside the window
nearest the source
Exterior maximum sound
level for outdoor
entertainment - 85 dBA
Prohibition against
loudspeakers in rights-of-way
and air space
Noise disturbances of such
character, intensity and
duration as to be and tending
to be detrimental to the life,
health, or normal comfort
to annoy or disturb the quiet,
comfort and repose
SA
“
Siebein Associates, Inc.
Appendix A-4
No.
City
State
34
Tucson
35
World Health
Organization
SA
“
Arizona
Day
time
dBA
70
72-comm
85Ind.
Night
time
dBA
62
65comm
70Ind.
dBC
Octave
band
levels
Plainly
Audible
Other
provisions
Allowing or causing any
conntinous or intermittent
noise that persists for a
period of at least 15 minutes
and which is caused by using,
operating or permitting to be
played any radio, television,
tape deck, record player,
amplifier, musical instrument,
or instrument, machine or
device used for production,
reproduction or emission of
sound.
55-Outdoor
35-Indoor
Siebein Associates, Inc.
Appendix A-5
TECHNICAL ACOUSTICAL ISSUES FOR
NOISE ORDINANCE DEVELOPMENT
Gary W. Siebein, FASA, FAIA
Senior Principal Consultant
Siebein Associates, Inc.
Professor of Architectural and Environmental Acoustics
University of Florida School of Architecture
When the early morning light quietly grows above the mountains . . .
When the little windwheel outside the cabin window sings in the gathering thunderstorm . . .
4 Standards to be applied
When the wind, quickly shifting, grumbles in the rafters . . .
1. OSHA levels that cause hearing damage
When the mountain brook in the night’s stillness tells of its plunging over the boulders . . .
2. Levels that cause health effects other than
hearing loss
When one morning the landscape is hushed in its blanket of snow . . .
3. Levels that cause sleep disturbance
When the cowbells keep tinkling from the slopes of the mountain valley where the herds wander sl
.. .
4. Annoyance
Martin Heidigger The Thinker as Poet
Annoyance
Complex physical
and psycho social
phenomenon
Level
Duration
Relation to noise
Health Effects Of Noise
OSHA Occupational Noise Exposure Levels
(other than hearing loss)
Diseased
population
Healthy
population
1
NORMALLY HARMFUL SOUNDSCAPE
NORMALLY HARMFUL SOUNDSCAPE
90 dBA OSHA
Wear HPD’s
90 dBA OSHA
Wear HPDS
80 dBA EU
Hearing Limit
80 dBA EU
Hearing Limit
75 dBA
75 dB A
TRANSITION BETWEEN NOWMALLY HEALTHY & NOAMLLY HARMFUL
65 dBA HUD,
FAA FHWA
Outdoors
TRANSITION BETWEEN NORMALLY HEALTHY & NORMALLY HARMFUL
65 dBA HUD, FAA
FHWA Outdoors
55 dBA EPA
Outdoors
55 dBA EPA
Outdoors
45 dBA HUD
FAA Indoors
45 dBA. HUD
FAA Indoors
NORMALLY HEALTHY SOUNDSCAPE
NORMALLY HEALTHY SOUNSCAPE
30 dBA WHO
Indoors 20 dBA
WHO 30 dBA.
Indoors 20 dBA
DESIGN CRITERIA
Environmental Noise Intrusion
OUTDOORS
NORMALLY HARMFUL SOUNDSCAPE
90 dBA OSHA
Wear HPD’s
FEDERAL AGENCIES - HUD, FAA, FHWA
LDN – Day Night Average Sound Level
65 dBA outdoors
45 dBA indoors
80 dBA EU
Hearing Limit
75 dBA
TANSITION BETWEEN NORMALLY HEALTHY & NORMALLY HARMFUL
65 dBA HUD,FAA
FHWA Outdoors
55 dBA EPA
Outdoors
45 dBA
HUD FAA
Indoors
EPA
55 dBA LDN
MUNICIPAL NOISE ORDINANCES
55-60 dBA Day time sound level limits
50-55 dBA Night time sound level limits
Sometimes octave band limits or penalties for impulsive or tonal sounds
Different acoustical metrics – Lmax, Leq, L10, none specified
NORMALLY HEALTHY SOUND SCAPE
30 dBA WHO
Indoors 20 dBA
Plainly audible to person of normal sensibilities or loud, raucous, etc.
WHO
DESIGN CRITERIA
Indoor Sound Levels
HUD, NAHB, FAA -
Long term LDN 45 dBA
ASHRAE –
general noise
plumbing noise
Annoyance relative to ambient
Lmax
Reasonable Standard of Care
What are others doing in similar buildings
in locality
Sleep disturbance
WHO Night time
Leq
Organization for Economic
Cooperation and Development
European Community
Commission
Griefahn and Osada
RC, NC 25 -35 (32-42 dBA)
< 35 dBA
< 30 dBA
Leq
< 35 dBA light sleep
Leq
< 50 dBA deep sleep
Leq
< 30-35 dBA
Lpeak < 45 dBA
Lpeak < 60 dBA
▪ COMMUNITY NOISE ISSUES
Noise
▸
▸
1.Damages hearing
2.Interferes with sleep
▸
3.Health effects in addition to hearing loss
▸
4.Interferes with work tasks
▸
5.Interferes with speech and communication
▸
6.Causes annoyance
Disturbing to people who want to pay to fix it
2
▪Sources of community noise
1.Transportation sources
▪Community Noise varies in many ways and is
therefore very difficult to measure and predict.
2.Industrial sources
3.Entertainment sources
4.Construction noise
5.Domestic sources
6.Special sources
▸ 1.Time
▸
▸
▸
7.Natural sounds
often viewed as desirable by many people even
though the sound levels of these sources may be louder than intruding
sounds from industrial or entertainment facilities.
▪ Community Noise varies in many ways and is therefore very
difficult to measure and predict.
2.Location
3.Spectrum or frequency content
4.Daily and seasonal variations
–
–
–
–
–
Day and night variations in traffic noise and other ambient sounds
variation in use of facilities
Seasonal use patterns
Wind, temperature, weather and other effects
Loss of foliage from trees in winter
▪A community must deal with several essential
questions in this regard.
▸
1.How to define noise
▸
2.How to measure it
▸ 3.How to decide which sounds should be limited and which
should be permitted because many sounds that occur at the same
level may be necessary to the functioning of the community and
many may represent a disturbance
▸
▪ Three methods to control community noise
4.How to reduce or control the noise
▪ Three methods to control community noise
▪ 2.Noise Ordinances --Control the propagation of sound from
one property to another
▪ 1.Zoning --Locate noisy activities away from activities
requiring quiet
–Require buffers between properties
–Place restraints in development orders and development stipulations requiring limits
on production of noise, time of use restrictions or requirements for noise attenuation
–Usually on a complaint basis
–Plainly audible
–Loud, raucous, disturbing
–Quantitative sound level limits
– Overall sound level limits dBA or dBC
– Octave Band limits
– Penalties for tones or impulse sounds
– Other metrics used include Lmax, L50, L10 for some time duration, etc.
3
SPECIFIC ACOUSTIC EVENT
Sounds that can be individually identified and
measured
▪ Three methods to control community noise
▪ 3.Building codes--Tie building codes with planning and zoning
approvals and post construction noise ordinances to require
testing and certification of acoustical performance at the time of
Basic Components
•Source - voice, musical instrument, etc.
CO
•Path - air, building materials, etc.
•Receiver - ear, microphone, etc.
Sounds
travel
through a
medium or
substance
Amplitude
Frequency
▪ Associated with perceived loudness
▪ Magnitude of pressure change between wave rarefaction and
compression
▪ Associated with perceived pitch
▪ Measured in Hertz (Hz) or cycles per second (cps)
Typical sounds and their levels
Click to hear a
4000 Hz tone (High
Frequency)
Amplitude
4000 Hz
Compression
One Cycle
Click to hear a 100
Hz tone (Low
Frequency)
Rarefaction
100 Hz
Wave Rarefaction
DECIBEL ADDITION
Tone and Harmonics
Examples:
Rule of Thumb Method
▪ Tone
Single Frequency
(Fundamental)
–Contains only one frequency
▪ Complex Tone
–Contains a fundamental and additional
harmonics
Tone
Fundamental
▪ Harmonics
–Whole number multiples of the fundamental
frequency
Complex
Harmonics
Complex sound
1 Sec.
2 Hz Wave
Wave Compression
Difference
between measurements
0 to 1
2 to 3
4 to 8
9+
Add to Larger
Measurement
3 dB
2 dB
1 dB
95
95
89
99
89
91
98
99
93
0 dB
Methods to correct for ambient sound levels must
use decibel or logarithmic addition
Sound level increments
4
CHANGES IN SOUND LEVEL
GENERAL TYPES OF NOISE ORDINANCES
Perception of
Change
Change in
Level
‰ Overall Sound Level Limit
‰ Overall A-Weighted Sound Level Limits
‰ Overall C-Weighted Sound Level Limits
1 dB
undetectable
2-3 dB
barely perceivable
5-6 dB
definitely louder
10 dB
twice as loud
•Small changes
are subtle
•Substantial
increases in
power are need
to effect a
perceptual
change
‰ Octave Band Sound Level Limits
‰ Plainly Audible
‰ Maximum Sound Level Relative to Ambient
‰ Nuisance
‰ Multi-Tiered or Multiple Method
‰ Limits on Interior Sound Levels in Places of Entertainment
10 times the power is perceived as
twice as loud
OVERALL SOUND LEVEL LIMITS
OVERALL C-WEIGHTED SOUND LEVEL LIMITS
‰ Overall A-Weighted Sound Level Limits
‰ Very small amounts subtracted from low and high frequencies to simulate
the response of the human ear to fairly loud sounds
‰ Overall C-Weighted Noise Level Limits
‰ Usually enacted to account for low frequency sounds found in deep, bass
music or equipment noise
OVERALL A-WEIGHTED SOUND LEVEL LIMITS
‰ Limits propagation of sound from one property to another
‰ Lower limits at residential property lines than at commercial property lines
‰ Lower limits for night time hours than day time hours
Comparison of AWeighted, C-Weighted
and Flat Weighting Curves
10
Flat Response
0
Sound Level (dB)
C-Weighted Curve
The A-Weighted sound
level reduces the low
frequency sound energy
-10
-20
A-Weighted Curve
-30
OCTAVE BAND SOUND LEVEL LIMITS
‰ Limits to define a disturbing noise
‰ Provide precision at a moderate cost
‰ Requires highly trained personnel to interpret measurements
‰ Provides suitable documentation for prosecution
‰ Provides adequate information to a consultant to prescribe remedial
measures to reduce propagated sound
-40
-50
31.5 Hz
63 Hz
125 Hz
250 Hz
500 Hz
1000 Hz
2000 Hz
4000 Hz
8000 Hz
1/3 Octave Band Center Frequency (Hz)
Flat
C-Weighted
A-Weighted
RANGES OF FREQENCIES
FREQUENCY BANDS
Decibels
•1/3 Octave band
frequency centers
80
•Octave band
frequency centers
70
60
50
40
30
32
63
125
250
500
1000
2000
4000
frequency band centers
An octave band is a group of frequencies
where the higher frequency is twice the
lower frequency
125 Hz to 250 Hz for example
8000
16000
8 Octave bands (63 Hz to
8,000 Hz)
25 1/3 Octave band
frequency centers (63 Hz to
16,000 Hz)
5
PLAINLY AUDIBLE
PEAK, MAXIMUM AND AVERAGE TIME LEVELS
‰ Plainly audible to a person of normal sensibilities
¾ At a certain distance from the sound
¾ At the property line of the receiver
MAXIMUM SOUND LEVEL RELATIVE TO THE AMBIENT NOISE LEVEL
‰ Advantages
¾ Provides a sliding reference scale that accurately represents the relative
sounds of the environment of the source sound
¾ Relates the magnitude of the disturbing sound above the ambient at the
time and place of the complaint
‰ Disadvantages
¾ Requires 2 measurements to be made (disturbing sound and ambient
sound)
¾ Requires a comparison to be made between the 2 measurements at the
site of the violation
CASE STUDY 1
Amplified Music Noise
Amphitheater located
near homes
Loud music disturbs
residents
BURIED IN THE AMBIENT?
Pink – ambient noise
Blue – music playing
Ford Amphitheater Noise Study - Hank Williams, Jr. Concert - January 29, 2005
Location: Wexford Wilson Apartments
Music from Concert:
64 to 76 dBA
70
60
EPC Rule:
60 dBA
Typical Ambient Only:
58 to 60 dBA
50
8:31:24
8:31:22
8:31:20
8:31:18
8:31:16
8:31:14
8:31:12
8:31:10
8:31:08
8:31:06
8:31:04
8:31:02
8:31:00
8:30:58
8:30:56
8:30:54
8:30:52
8:30:50
8:30:48
8:30:46
8:30:44
8:30:42
8:30:40
8:30:38
8:30:36
8:30:34
8:30:32
40
8:30:30
Sound Pressure Level, dBA, re: 20 micropascals
80
Time, PM
Concert Music + Ambient (Lmax)
Ambient Between Songs (Lmax)
6
BURIED IN THE AMBIENT?
Ford Amphitheater Noise Study - Hank Williams, Jr. Concert - January 29, 2005
Location: Wexford Wilson Apartments
Music from Concert:
64 to 76 dBA
80
10.0
8.0
dBA, Relative to 1 min LAeq
Music - Ambient:
62 to 76 dBA
70
60
EPC Rule:
60 dBA
Typical Ambient Only:
58 to 60 dBA
50
Ford Amphitheater Noise Study - Hank Williams, Jr. Concert - January 29, 2005
Comparison of Measurement Metrics - Staley Estates Data
12.0
10s LAeq = 60.5 dBA
6.0
EPC Rule:
60 dBA
4.0
2.0
0.0
-2.0
1min LAeq = 57 dBA
-4.0
21:31:51
21:31:53
21:31:57
21:31:49
21:31:55
21:31:55
21:31:47
21:31:53
21:31:45
21:31:51
21:31:43
21:31:49
21:31:41
21:31:39
21:31:37
21:31:35
21:31:33
21:31:31
21:31:29
21:31:27
21:31:25
21:31:23
21:31:21
21:31:19
21:31:17
21:31:15
21:31:13
21:31:11
21:31:09
21:31:07
21:31:05
21:31:03
8:31:24
8:31:22
8:31:20
8:31:18
8:31:16
8:31:14
8:31:12
8:31:10
8:31:08
8:31:06
8:31:04
8:31:02
8:31:00
8:30:58
8:30:56
8:30:54
8:30:52
8:30:50
8:30:48
8:30:46
8:30:44
8:30:42
8:30:40
8:30:38
8:30:36
8:30:34
8:30:32
8:30:30
40
21:31:01
-6.0
21:30:59
Sound Pressure Level, dBA, re: 20 micropascals
NOT ALL dBA’
dBA’s ARE CREATED EQUAL
Time
1min LAeq
10 Sec LAeq
Time, PM
Concert Music + Ambient (Lmax)
Concert Music - Ambient
Ambient Between Songs (Lmax)
NOT ALL dBA’
dBA’s ARE CREATED EQUAL
Ford Amphitheater Noise Study - Hank Williams, Jr. Concert - January 29, 2005
Comparison of Measurement Metrics - Staley Estates Data
12.0
10.0
12.0
1s LAeq = 63 dBA
1s LAmax = 67 dBA
10.0
10s LAeq = 60.5 dBA
6.0
1s LAeq = 63 dBA
8.0
EPC Rule:
60 dBA
4.0
dBA, Relative to 1 min LAeq
2.0
0.0
-2.0
1min LAeq = 57 dBA
10s LAeq = 60.5 dBA
6.0
Ordinance:
60 dBA
4.0
2.0
0.0
-2.0
-4.0
1min LAeq = 57 dBA
-4.0
10 Sec LAeq
Lp Range
72 to 89 dBA
16
80 to 85 dBA
11
Enforcement Method 2
73 to 88 dBA
8
77 to 83 dBA
5
55
73 to 85 dBA
15
70to 83 dBA
1s LAmax, Fast
66 to 89 dBA
63 to 85 dBA
Song 1
Lp Range
Lp Range
21:31:57
21:31:47
21:31:45
21:31:43
21:31:41
21:31:39
21:31:37
21:31:35
21:31:33
21:31:31
21:31:29
21:31:25
21:31:23
21:31:21
21:31:19
21:31:17
21:31:15
21:31:13
21:31:11
21:31:09
21:31:27
Time
1 Sec LAeq
1 Sec LAmax
‰ Prohibit sound levels deemed to be “loud, raucous, or
otherwise disturbing the peace, quiet, repose” etc., of the
community
61
20
Song 2
# of 84 dBA Exceedences*
10 Sec LAeq
NUISANCE
# of 81 dBA Exceedences**
Enforcement Method 1
1s LAmax, Slow
21:31:07
1min LAeq
Song 2
# of 84 dBA Exceedences*
21:31:05
1 Sec LAeq
Song 1
Lp Range
-6.0
21:31:03
Time
1min LAeq
21:31:01
21:31:57
21:31:55
21:31:53
21:31:51
21:31:49
21:31:47
21:31:45
21:31:43
21:31:41
21:31:39
21:31:37
21:31:35
21:31:33
21:31:31
21:31:29
21:31:27
21:31:25
21:31:23
21:31:21
21:31:19
21:31:17
21:31:15
21:31:13
21:31:11
21:31:09
21:31:07
21:31:05
21:31:03
21:31:01
21:30:59
-6.0
21:30:59
dBA, Relative to 1 min LAeq
8.0
# of 81 dBA Exceedences**
L5
84 dBA
0
82 dBA
1
L10
83 dBA
0
81 dBA
0
L50
78 dBA
0
79 dBA
0
Full Song Overall LAeq
80 dBA
0
79 dBA
0
MULTI-TIERED
‰ Combination of plainly audible language with A-Weighted sound level limits
‰ Series of specific prohibitions
‰ Language stating that the most stringent requirements prevail
LIMITS ON INTERIOR SOUND LEVELS IN CLUBS
‰ Los Angeles
* Only used values that exceeded 84.4 dBA
** Only used values that exceeded 81.4 dBA
¾ Sound level limited to 95 dBA
‰ Gainesville, Florida
¾ Sound levels limited to OSHA limits
Song 1: 5 minutes, 48 seconds long = 24 total 15 second periods
Song 2: 3 minutes, 23 seconds long = 13 total 15 second periods (last 8 seconds was quiet ending)
‰ New York City, New York
¾ Sound levels limited to 45 dBA in adjacent buildings
7
SPECIAL PROVISIONS IN THE NOISE ORDINANCES REVIEWED
‰ Night Time Hours Defined
‰ Distance Requirements
‰ Plainly Audible Clarified
‰ Unenclosed Places of Public
Entertainment Defined
‰ Provide Sound Insulation in Homes
and Businesses
• Consider specific exemptions and prohibited
acts
• Consider allowable hours of operation for
hospitality establishments with outdoor dining
and music
• Cite appropriate ANSI and ASTM standards for
measurement protocols required
• Tie Noise Ordinance requirements to Planning and
Zoning review of proposed projects and Building Permit
applications
• Require Environmental Acoustic Assessments by NCAC
or INCE member firms for future residential and
commercial/hospitality projects in downtown to identify
possible noise issues before projects are built
• Require acoustical measurements at Substantial
Completion of project to verify compliance with Noise
Ordinance prior to occupancy
• Enact a 6 month trial period for Noise Ordinance
with committee re-convening to assess strengths
and weaknesses prior to final adoption
• Develop Standard Operating Procedure for
enforcement personnel
• Conduct training, purchase meters etc. for
enforcement personnel
Provide rational, measurement based data as the basis for sound
level limits and districts in the Ordinance
8
The Acoustics of Mixed Use New
Urbanist Centers is a Potential
Nightmare
QUIET COMMUNITIES
QUIET COMMUNITIES
Simplified 3 Part Acoustical Palette for
Community Soundscape Design
Reduce, buffer mitigate noise
Preserve and enhance desirable sounds
Design for new sounds and social spaces
Vehicle to allow integration of
Architectural
Urban Design
Acoustical Schemes
In a participatory, scientific and interesting
process for community design
Meet existing laws
Plan for and design community
soundscape
Provide for a better tomorrow
. . . “Always the wish that you find patience enough in
yourself to endure, and simplicity enough to believe,
that you may acquire more and more confidence in
that which is difficult, and in your solitude among
others” . . .
Rainier Maria Rilke Letters to a Young Poet 1954
Make your community sing!
THANK YOU !
Gary W. Siebein, FASA, FAIA
Senior Principal Consultant
Siebein Associates, Inc.
Professor of Architectural and Environmental Acoustics
University of Florida School of Architecture
Phone. 1-352-331-5111 x16 (Office)
Email. gsiebein@siebeinacoustic.com
9