HomeMy WebLinkAboutAgenda - 11-22-2004-c1ORANGE COUNTY
BOARD OF COMMISSIONERS
PUBLIC HEARING ITEM ABSTRACT
Meeting Date: November 22, 2004
Action Agenda
Item No. 0 , g
SUBJECT• Proposed revisions to the County Noise Control Ordinance
DEPARTMENT: Planning and Inspections PUBLIC HEARING: (YIN) Yes
ATTACHMENT (S):
Comparison of Community Noise
Ordinances in North Carolina (pp 3 - 10)
Existing Orange County Noise Ordinance
Comparison Chart (pp 11 -15)
Article entitled "Sound Advise" (pp 16 - 32)
The existing noise control ordinance (pp
33 - 37)
INFORMATION CONTACT:
Lindy Pendergrass, Sheriff, ext 2900
Craig N, Benedict, Director, ext 2592
Glenn Bowles, Planner II, ext 2577
TELEPHONE NUMBERS:
Hillsborough
Chapel Hill
Durham
Mebane
732-8181
968-4501
688-7331
336-227-2031
PURPOSE: To hear citizen comments and Administration recommendations concerning the
possible noise control ordinance amendments.
BACKGROUND: In recent years a number of citizen complaints regarding noise have been
received by the Sheriffs Office and the Planning Department. The present ordinance, which
the Sheriffs Office enforces, does not adequately address some situations, such as noise
generated from recreational motorized vehicles (i.e., ATVs, motor bikes, go-carts, model boats
and planes) and the like, which have generated citizen complaints. The situation is not a point
of regulation, but rather a community problem - a nuisance for which a "reasonable neighbor"
approach is suggested.
Discussion regarding the noise control ordinance should address amendments which:
1. Provide simplification to the definitions section,
2. Provide more detailed noise standards,
3. Clarify how noise measurements are to be taken,
4, Add additional activities to the list of exempt activities,
5. Add a list of nuisance noises to the ordinance, and
6. Prescribe higher penalties,
The Planning Board briefly discussed this noise ordinance and citizen complaints at its October
6 meeting as a point of information to garner perspective on the issue but not as a regulatory
item since it is within the purview of the Sheriff and BOCG.
FINANCIAL IMPACT: No financial impact at this time with human resources being used from
existing department staffs.
RECOMMENDATION (S): The Administration recommends that the Board close the public
hearing and adopt an amended nose control ordinance.
This item does not require a recommendation from the Planning Board since it is not a zoning
or subdivision ordinance.
Clarification of the Attachments
The attachments include the following items:
1. A comparison chart of noise control ordinances from otherjurisdictions, including Orange
County, which is found on pages 3 through 10;
2. A comparison chart of the existing Orange County Noise Control Ordinance with
suggested and alternative revisions to the appropriate articles, which is found on pages
11 through 15;
3. A timely article entitled, "Sound Advice, which is found on pages 16 through 32;" and
4. The existing Orange County Noise Control Ordinance, as amended, which is found on
pages 33 through 37,
Several examples of North Carolinian noise control regulations are provided so that
Commissioners can gain perspective regarding how other counties, towns, and cities address
noise control, The Orange County chart also includes the zoning ordinance noise performance
standards and the Town of Chapel Hill's noise standards of different sound frequency bands.
"Sound Advice" is a very readable and understandable article, which was written to help make
noise control and the technicalities of the science of noise more knowable to the normal person.
Finally, the existing Orange County Ordinance, which was adopted in 1983 and amended only
once since then, is included.
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City Of Any sound which The operator must have received special Measurement of A- Blowing horns Lawn mowers Residential or Public- 60 dB(A) Special permits $100 for first
Fayetteville exceeds the limits training in sound measurement from an weighted sound level Radios, phonographs Agricultural day offense and $150
set forth in the expert in sound measurement and must as provided shall be Pets equipment --55 dB(A) night Bazking dogs for each
ordinance have received training in the use of the made with a Quest Use of vehicles Non-amplified subsequent
sound level meter used, as prescribed by Model 215 Sound Blowing whistles crowd noise Commercial Radios, tape offense in a 12-
the Chief of Police. Sound level Level Meter, a 3M Construction -- 65 dB(A) day players, month period.
measurement, to include A-weighted and Noise Enforcement operations with -- 60 dB(A) night Loudspeakers, or
octave band measurement, and recording Sound Level Meter building permits sound amplifiers
of measurement readings shall be Model .3220, or Noises of safety Industrial
according to procedures adopted by the equivalent, according signals, warning --75 dB(A) anytime Responsibility of
Chief of Police and shall conform to the to American National devices, and the Chief of Police
operating instructions included in the Standazds Institute emergency Sound frequency tables by Use and
operator's manual. (ANSI) standazds. pressure valves Time of Day also used.
Sound octave band Church bells and
measurements shall be chimes
made with a Quest Authorized
Mode1215-45 Octave emergency
Band Analyzer, or its vehicles
equilavent according Normal operations
to ANSI standazds. of aircrafr
Any use receiving
a ermit
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Johnston/
Forsythe
COllntleS
any unreasonable
loud and
disturbing noise is
prohibited and
unlawful. Noise
of such character,
intensity, and
duration as to be
detrimental to the
health, safety, or
welfare of any
individual is
prohibited
Loud, boisterous or Noises generated, made, or created during the regular
raucous language or operations of a manufacturing or industrial facility
shouting Fire, law enforcement, ambulance, rescue, or other
Sounding of any emergency vehicle noise
hom or signal device Parades, fairs, circuses, or other similar public
n any vehicle, except entertainment events
as a danger signal or ConstmcNon operations
as required by law Normal operations of aircraft
Playing of any radio, Lawn mowers, agricultural, and landscaping equipment
television set, record Emergency work
player, musical Provision of governmental services
inshvment or sound Holiday noisemakers and fireworks
-producing or Trains and associated rolling stock
sound-amplifying
device ...
Keeping of any
animal, which.. ,
shall disturb the
comfort and repose
of any people of
sensibility in the
vicinity
Any unrepaired
vehicle in such a
manner as [o create
loud grating,
grinding, rattling or
other noise.
Durham It sha116e unlawful for any person to make, pemtit, continue, or cause to be made or to create any The following factors incident to such noise are to be considered: time of day; proximity to residential
COUnty umeasonably loud and disturbing noise or noise which is substantially incompatible with the time structures; whether the noise is recurrent, intermittent, or constant; the volume and intensity; whether
and location where created to the extent that it creates an actual or eminent interference with peace the noise has been enhanced in volume or range; the character and zoning (if applicable) or the area;
and good order and which is perceived by a person of ordinary sensibilities as interrupting the whether the noise is related to the normal operation of a business or other labor activity; whether the
normal eace and calm of the area. noise is sub'ect to bein controlled without unreasonable effort or expense to the creator thereof.
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Jurisdiction Noise Location Methodolo Instrumentation Prohibited xcep
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or
Orange No person shall Noise Sound level Sound level meters Construction operations from 7 a/m/ to 9 Receiving land Orange
Conn
t3' operate or cause to measurements measurement shall shalt be of at least p m on weekdays and 8 am to 9 p m on - 60 dB (A) 8 am. to I l COllRty Sheriff
be operated any shall be taken at be made with a Type 3 meeting ANSI weekends covered by a permit pm.
source of sound in the comer of the sound level meter S 1 4 -1971 Safety signals, warning devices, 50 dB(A) I 1 p m. to 8 a.m
such a manner as primary structure using the "A" requirements. The emergency pressure relief valves, and (Sunday through Thursday)
to create a sound of the complainant weighting scale set entire sound church bells
level which nearest the noise on "slow response." measurement system Authorized emergency vehicles
exceeds the levels source, but when shall be serviced and Street fairs with a permit
set forth below this location is not operated as Normal aircraft operations
when measured as pmetical noise recommended by the Vehicles with properly equipped
specified, measurements manufactures Persons manufacturers' standazd mufflers and
shall be made at using the sound level noise reducing equipment
the boundary of meters shall be trained Lawful fireworks and noise makers during
the public or in sound level a holiday
private right-of- measurement and the Lawn mowers and agricultural equipment
way, which operation of sound
adjoins the level meters
complainants'
ro erty.
Alamance Unlawful for any person or persons to In determining whether a noise is unreasonably loud and disturbing, Farrning By injunction or 550.00 or
COllIIty make, permit, continue, or cause to be the following factors incident such noise aze to be considered: time of operations other equitable imprisonment of
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made or to create any noise which is day; proximity to residential structures; whether the noise is recurent, relief by an action ot
.
30 days or
substantially incompatible with the time intermittent, or constant; the volume and intensity; whether the noise brought in the
and location when created to the extent has been enhanced in volume or range; [he character and zoning; General Court of
that it creates an actual or imminent whether the noise is related to the normal operation of a business or .Justice..
interference with peace or good order other labor activity; whether the noise is subject to being conrolled
and which is perceived be a person of without unreasonable effort or expense to the creation thereof.
ordinary sensibilities as interrupting the
Horn, ease, and calm of the area.
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Jurisdiction Definition of Measurement of Sound Unlawful Acts Maximum Levels by
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Buncombe Unlawful for any person or persons to Tn determining whether a noise is Blowing horns Safety signals and Sheriff of Not more than
l =0llnty make, permit, continue, or cause to be unreasonably loud and disturbing, the Radio, record warning devices Buncombe County 5200.00
made or to create any noise which a following factors incident such noise aze to be players, etc. Authorized
reasonably prudent person would considered: time of day; proximity to Pets emergency
consider or find substantially residential structures; whether the noise is Use of vehicles vehicles
incompatible with the time and location recurrent, intermittent, or constant; the Blowing whistles Emergency work
where created to the extent that such volume and intensity; whether the noise has Exhaust dischazges Normal operations
noise creates an actual or imminent been enhanced in volume or range; the nature Compressed air of any commercial
interference with the peace, dignity, or and zoning of the area; whether the noise is devices or industrial
good order in the immediate area where related to the normal operation of a business Discharging enterprise, except
created, or perceived by a person of or other labor activity or is the result of some firearms amplified sound
ordinary sensibilities as interrupting the use for individual purposes; whether the noise Building operations Farming
normal peace and calm of the area, and is subject to being controlled without Noises near schools operations
any excessive or unusually loud sound unreasonable effort or expense to the creation Loading and Shooting range
or any sound which is of such chazacter, thereof. unloading operations operations
intensity, and duration as to disturb the Bells and gongs Community
peace and quiet of any neighborhood or Hawking, peddling, celebration of
which disturbs, injures ore endangers the and soliciting national, state,
comfort, repose, health, peace, or safety Blowers and engines county events or
of any person and being a type of sound Appliances and public festivals.
which could be lessened or otherwise other mechanical
controlled by the maker without unduly devices
restricting his conduct. Loudspeakers or
am ]ifiers
Catawba The creation of any unreasonably loud, Amplification Noise of such character, intensity and duration Blowing horns, Lise of vehicle, Pets, Radios, Atl noise generated as the result of the
~Onnty disturbing, and unnecessary noise in the pemvts are as to be detrimental to the health, safety or phonographs, etc., Loud language, Building noises, normal day-to-day operations of a
county is prohibited. required. welfaze of any individual is prohibited. Engine noises, Loudspeakers, amplifiers, or other devices, properly zoned and pemtitted
Fireworks, fire arms commercial, farm, or industrial
ente rise, or ovemmental facility.
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Town Of No person or At any point on The town manager Sound level meters Yelling, shouting, Sound from regulazly am pm Town manager or Up to 5500.00
group of persons the boundary or his designee shall be of at least whistling, or singing scheduled athletic the town per day and [he
Chapel Hill Res 50 45 '
shall operate or planes of the shall issue a Type 2 as defined in Noisy parties events . manager
s town may
cause to be property line from general order ANSI S1.4 -1997 for Landing operations Construction operations designee institute legal
operated any which the sound adopting standazds integrating-averaging Repair of motor Safety signals, warning procedures for
source of sound in originates or and procedures for sound level meters. vehicles devices, emergency injunctive relief
such a manner as beyond sound level The sound Sound amplification pressure relief valves,
to create a root measurements and measurement system equipment church bells
mean squaze consistent shall be serviced and Homs and signaling Authorized emergency
steady-state sound enforcement calibrated and devices vehicles
level that exceeds operated as Vehicles without Street fairs
the limits set forth recommended by the original Normal aircraft Comm. 65 55
when measured manufacturer or as manufacturers' operations
outlined. Persons muffler or Normal vehicle
using the sound equivalent operations
measuring equipment Exterior and mobile Lawful fireworks and
and related toad speakers noisemakers on
instrumentation shall Power equipment holidays and at
be trained in its Explosives religious ceremonies
proper operation, use, Security alarms Lawn mowers
and care.
Vehicle sound ,
agricultural equipment,
Indust.
70
65
systems and landscape
maintenance equipment
Music and firearms at
military ceremonies
Emergency work
Normal governmental
services
Sanitation and Also subject to frequency octave
recycling services restrictions by time of day, and land
use designation
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Chatham No person shall Noise Sound level Perrnit to exceed Construction operations Time Period W/ W/0 County Manager Not to exceed
COllnty outside the measurements measurement shalt be maximum Safety signals, warning Perrnit Permit shall assess civil $100.00 ($500.00
corporate limits of shall be taken at made with a sound permissible devices, emergency 8 a.m. to ] 0 60 60 penalties. in criminal
a city or town, the corner of the level meter using the standazds. pressure relief valves, p m, proceedings)
and within primary structure "A" weighting scale and church belts
"
Chatham County, of the set on
slow Authorized emergency ] 0 p.m. to t 0
operate or cause complainant response," And shall vehicles a. m, 50 50
to be operated any nearest the noise be of at least Type 3 Un amplified noises at
source of sou
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ANSI S
4
n
n source
w
en meet
ng
1.
- pemvtted street fairs Tr 5 p.m. to 10
such a manner as the location is not 1971 requirements of Normal aircraft
to create a sound
practical, noise
the latest approved
operations p m 70 85
level which measurements version thereof
The Pro
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exceeds the limits
shall be made at
entire sound
motor vehicles Fr 5 pm. to 12
set forth below the boundary of measurement system Lawful fireworks and 70 85
when measured as the public or the shall be serviced and noisemakers on
sped&ed. private right-of- operated as holidays Sat 12 a.m. to 1
way, which recommended by the Lawn mowers and am. 60 85
adjoins the manufacturer. agdculmral equipment
complainant's Persons using the Sat 5 p. m. to 12
property sound level meters am. 70 85
shall be trained in
sound level Sun 12 a.m. to I
measurement and the am.
operation of sound 60 85
level meters.
City Of It shall be The following activities within 300' of any Noises not exceeding 9 a m 9 p.m., Pernrits for Up to $500.00
Charlotte unlawful for any occupied residential structure: 60 dB(A) Use to 9 to 9 additional and/or
person to create or
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ass
st
n creat
ng 2. Construction machinery at night Am
p A police officer, up to 30 days.
any unreasonably
d a
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n
ou .avm mowers or
omestic tools at ni ht
g Multi- officer, or animal
disturbing noise. 5, Mechanical noise louder than 60 dB(A) 55 50 control officer
Family
Public Enter- 65 50
tainment
Adver- 60 60
tisin
Public 60 50
r. o w.
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McCklenbUrg It shall be For the purpose of Animals or motor 9 am 9 p m. Permits for Not to exceed
COUnty unlawful for any determining decibel vehicles Use to 9 to 9 additional $100.00 ($500.00
person to create or levels (dB(A)) ,the .m. a.m. amplification. A in criminal
assist in creating noise shall be police officer or proceedings)
any unreasonably measured on the A- fiquip. 55 50 anima] control
loud and weighting scale on a officer.
disturbing sound level meter of
Multi-
noise. standard design and
Family 55 50
quality, meeting the
standards prescribed Public Enter-
by ANSI
tainment 65 50
Adver- 60 60
tising
Public 60 50
r.o w.
Public Parks 75 65
New Hanover Noise measurements shat] be made at Calibrate the meter Animals, Motor vehicles in disrepair, Noise Emergency operations, 7 am ] 0 p m $100.00 first
COUnty the nearest comer of the complaining within one hour on any street adjacent to any school, Aircraft operations at to 10 to 7 offense, $300..00
primary stmcture but when the before use. Set the institution of teaming, library, hospital or the county airport .m. am. second offense,
measurement in such location is not meter on the "A" court or church, Construction machinery, $500..00 for each
pmetical, noise measurements maybe weighted network. Gazage machinery, Lawn mowers and other Non- additiona]
made at the boundary of the public Set the domestic tools, Yelling, shouting, whistling, Residential 75 70 offense
right-of--way, which adjoins the omnidirectioal or singing, Sound-amplified devices
complaining property. Such noise microphone in an
measurements shall be made at a height approximately 70°
of at least 4' above the ground and at a position
point approximately ] 0' away from
walls, barriers, or obstructions. No Residential 65 50
individual other than the operetors shad
be within ] 0' of the meter during the
sam le eriod.
Rowan Any sound which annoys or disturbs The county sheriff s deparhnent and any other county
COUnty humans, or which causes, or tends to sanctioned law enforcement agency.
cause, an adverse psychological or
h siolo ical effect on humans.
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City Of Any excessive or Noise Sound Any instrument Section 12-5007 Emergency warning Zoning 7 am. 1 I p m Not to exceed
Ralei h
g unusually loud measurements measurement shall certified to meet or devices or safety to 1 I to 7 a.m $100.00 ($500.00
sound or any shall be made at be conducted at exceed ANSI signals p m. in criminal
sound which the property tine that time o£day or standards, which Lawn care and proceedings)
disturbs the peace of the property night when the includes an agricultural field
and quiet of any where the noise to suspect noise omnidirectioal equipment
neighborhood or be measured is source is emitting microphone, an Equipment used for
which does being generated. sound. The meter amplifier, an output construction
annoy, disturb, If measurement shall be calibrated meter, and frequency Pazades, fairs, circuses, Residential 55 45
injure, or on private pro- within one hour weighting network(s) other similaz public
endanger the perry is not before use and for the measurement entertainment events,
comfort, repose, possible or prat- recalibrated after of sound level. sanctioned sporting
health, peace, or tical, measure- use. The meter events sporting
safety of any menu may be shall beset on the activities
person or causes made at the boun- "A" weighted Be11s, chimes and
damage to dary of the public network at slow similar devices
property or right-of--way response and in an Emergency work
business. which adjoins the approximate 70° Electrical transformers
complaining pro- position . The Public right-of--way Commercial 60 55
perty and shall be operator shall face sources
made at a height [he noise source
of at least 4' and record the
above the ground meter's
d
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an
aY a po
nt nstantaneous
approximately 10' response observed
away from walls, at consecutive ] 0-
barriers, and second intervals
obstructions, until 100 reading
operated on the are obtained. Industrial 70 65
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network.
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___ 16
Attachment 3
Sound G~'dvice
Helpful Information from Stewart Glcoustical Consultants sfs-666-a6sg
copyright20D4
A member firm of the National Council of Acoustical Consultants www. sacna,com
7406 L Chapel Hill Road, Raleigh, NC 27607
The information in this document is not provided as a consulting service or as a solution to any specific problem.
EVALUATION OF
ENVIItONN1ENTAL SOUND IN THE COMMCUNTT'Y
By Noral D. Stewart, Ph.D.
Revision of February 27, 2004
There aze ancient references to noise being a problem in cities. In this century, noise was recognized as
a problem in cities in the 1920's. The sources were new modes of transportation, ventilation systems,
industrial plants, and loudspeakers.. The coming of,jet aircraft renewed interest in enviromnental noise.
With increasing population density, communities become noisier,.
There has been much research on problems related to noise in the community. Most of this has
concentrated on sources related to transportation, military systems, and ventilation systems. That is
because these sources are widespread, and there are readily available mechanisms to fund the research.
Most of this research has concentrated on establishing acceptable quantities of sound and reducing sound
to those levels for these common sources. However, most of the research has concentrated on densely
populated azeas where more noise is expected. Many of the criteria developed are aimed primarily at
evaluating whether certain land uses such as residentialcan be made compatible with a given level ofnoise.
Tlvs is a different matter than evaluatingwhether new noise is compatible with existing development. Some
criteria based onlong-termaveragesalso fail to recognize problems due to recurring loud events thatmay
only occur once a week.
Problems due to the amount of sound from a fixed source aze usually solvable with enough money. The
producer of the sound usually does not need or want the sound any more than neighbors who might be
complaining. Primary exceptions where it is most difficult aze sources involving outdoor entertainment or
recreation.
More recently, manufacturers ofmany products such as automobiles, appliances, and ventilation systems
have been paying more attention to "sound Quality." They have realized that once the quantity of sound
is reduced, the quality becomes important. People have an expectation for way sources should sound.
In quieter communities, this expected sound quality also becomes important. People expectto heaz ablend
ofsounds that become unnoticeable., Sounds that stand out and typically demand attention cause problems
ff they aze heard cleazly regardless of the level of sound. It is unportant to consider both the amount of
sound and the way it sounds. Problems due to the nature of a sound aze sometimes related to industrial
machinery that might have an impulsive chazacter or sound like a siren. The more difficult problems to
resolve aze those related to speech, music, or other recreational activities where the sound is desired by
the producers or their customers.
This documenthas evolved from work on several projects. Portions of this material have been and often
are incorporated into reports on major projects. It is intended to provide a basic primer on noise in the
community..
17
Aftachment 3
Environmental Sound
Page 2
Environmental Sound and its Measurement
Sound
The human ear is a remarkable mechanism.. It can sense and give meaning to a wide range of sounds
varying in loudness and pitch.. Perception is not directly related to the physics of sound.
The effect perceived by the ear as sound is a very small and rapid change in air pressure. The variations
aze very slightly above and below the barometric pressure. The perceived loudness of a sound
corresponds primazily to the size of this variation in pressure. The ear is very sensitive and can detect, at
some frequencies, variations less than 3 billionths ofa pound per square inch (psi). Variations greater than
0.001-.O1 psi can cause pain or discomfort. Notice that the pressure variation of the loudest sounds we
hear is about a million times that ofthe quietest sounds, The energy in the sound is actually related to the
squaze of the pressure. Thus, the energy in very loud sounds can be amillion-million times that in a very
faint sound,
For humans to heaz the sound, these air pressure variations must be rapid. They must complete a cycle
at least 20 times per second and not more than 20,000 times per second, The repetition rate of these
cycles is called the frequency of the sound. It has units of Hertz (Hz) where one Hz corresponds to one
cycle per second, The bass sounds in music are low-frequency, and the treble sounds are high-frequency,
Because of the wide range of sound pressures encountered, a special scale, the decibel scale, has been
developed. The sound level increases by 3 dB (or decibels) when the actual sound energy present is
doubled, Conversely, half the sound energy must be eliminated to reduce the level 3 dB. A six decibel
change indicates four times as much sound, and a 10 decibel change 10 times the sound. However, the
ear does not perceive these changes to be so large, Most people fmd a 3 dB change bazely noticeable,
A 6 dB change is cleazly noticeable, and a 10 dB change is perceived as a doubling or halving ofloudness,
This is very important, It means that 90% of a given sound energy must be eliminated before most people
will,judge a sound half as loud.
People do not hear very low-frequency and high-frequency sounds as well as they hear sounds in the
middle speech frequencies.. A specialelectronic filter is usedm sound meters to simulate this characteristic
ofthe eaz, For many environmental sounds it gives a simple, single-number descriptive level that correlates
with the way people judge the loudness ofthe sormd. This measure is called the A-weighted sound leveh
The units aze usually written dBA or dB(A).
18
Attachment 3
Environmental Sound Page 3
Outdoor Sound Propaeation
In the simplest idealizedmodel, the sound leveloutdoors decreases 6 decibels foreach doubling ofdistance
from the source. The farther one is from a sound source, the farther away one must go to notice a
significant decrease in sound level. In the real world, the sound level often decreases more rapidly with
distance. This is due to bazrieis blocking the line of'sight, absorption by the air, winds, and temperature
vaziations in the atmosphere, The atmospheric effects become most important at distances beyond about
1000 feetfrom the sowce. Dry air absorbs sound and reduces its level rapidly over distance.. The normally
humid environment in the southeastern U5 allows sound to travel further with less reduction in level.
Downwind and under many night-time conditions (cooler air near the surface), sound waves that start
upwazd will bend downward. Thus, the noise reduction benefits of barriers can be negated by these
atrnospheric effects, Levels will be lower upwind and under most daytime conditions. Sound waves curve
upwazd in the face of a wind or towazds cooler air higher in the atmosphere. For the same sound output
at the source, distant levels can be over 20 decibels less than predicted by the distance effects alone,
Sound Measurement
The basic instrument for sound measurement is the sound levelmeter. This is a microphone connected to
a voltmeter with some additional features, The microphone produces an electrical voltage signal
proportional to the sound pressure variation, and the voltmeter is calibrated to read the sound level in
decibels, Most meters have "fast" and "slow" responses, These aze effectively moving averages of the
sound leveh The fast response corresponds more closely to the actual fluctuating sound heazd, with the
needle sometimes moving very quickly or digital display changing rapidly, However, the slow response
provides a slowly changing indication that is easier to read. It averages the sound over about a second,
and commonly used for environmental sound measurements, The fast and slow response both introduce
some averaging into the measured result Some meters have a special "impulse" response that is used
primarily in Europe. VJhea a sound occurs very rapidly, such as a gunshot, 8 is sometimes desirable to
measure the peak pressure without any averaging, This is called the "peak" level. It is much higher than
the maximum level that might be measured with either the fast, slow, or impulse response,
It 's often useful to know the level of'the sound at different frequencies over the audible range, An
octave-band analyzer is most commonly used for this, It divides the audible frequency range into octave
bands (similar to musical octaves) so sound energy in each band can be measured, These bands are
identified by the center frequency of each band, The center frequency doubles for each higher frequency
band. Octave-band measurements can be A-weighted for a better indication of the contribution of each
octave to the A-weighted ]eveh However, they are not normally A-weighted ifused for comparison with
criteria based upon unweighted data, For diagnosing the source of sound, a finer resolution of frequencies
19
Attachment 3
Environmental Sound Page 4
is often desired The octaves aze often broken into one-third-octave bands, A finer resolution is provided
by aFast-Fourier-Transform analysis of the sound, T1vs can provide a resolution ofone Hertz or less that
can be related to a specific characteristic of a source.
When measuring typical fluctuating environmental sounds over long periods, it is common to use average
and statistical measures. One cannot simply write down severalmeasured sound levels and azithmetically
average the values. The energy average of 60 dB and 40 dB will be approximately 57 dB, half the higher
60 dB level. The energy equivalent average ]eve] over a given time is called the "time-average sound level."
It is also often called the "equivalent level," abbreviated LEQ, The averaging of sound levels can be
complicated unless one has a special instrument that does it automatically. Average levels over a period
due to individual events can be calculated by combining the "sound exposure level" (SEL) of the events,
The SEL is a measure of the sound energy of the event, It is the level in decibels of a sound of the same
energy lasting exactly one second.
The sound level during a given period also can be character'~zed bythe levelexceeded a givenpercentage
of the measurement period. For example, the levelexceeded 90% ofthe time is defined as the L90 value.
It is a good indicator of the background sound level. The L50 indicates the level exceeded half the time,
usually a little less than the time-average sound level. The higher sound levels are indicated by the levels
exceeded a small percentage of the time, Many localnoise ordinances developed before the widespread
availability of averaging meters were based on the L10, The L10 is usually a few decibels more than the
time-average sound level for varying sounds, The L10 can be less than the time-average sound level if a
very loud sound occurs less than 10% of the time. LOl indicates the highest levels likely to occur. The
difference between L01 and L90 or L10 and L90 is a good indicator of variation in sound levels, A
measurement period always must be specified for any statistical valnes such as LO1, L10 or L90 to have
meaning, The number of samples measured should be at least 10 times the difference in decibels between
the highest and lowest level.. Otherwise, different people measuring the same sound could get widely
varying results. Ideally, with automated instrvrrients there should be at least two samples per second with
slow meter response, and at least 16 samples per second with fast response. This gives a complete
description of the sound variation.
A special type of average sound level is used to describe the long-term acoustical climate of a location..
The Day-Night Average L.eve] is typically calculated over a yeaz, and has a 10 dBA night-time penalty
added to all sound between 10:00 p.m. and 7:00 a,m. This is abbreviated DNL, or sometimes LDN.
20
Attachment 3
Environmental Sound Page 5
DNL is most useful for planning purposes when noise does not change much from day to day. It faits to
identify some problems due to intermittent loud periods our undesirable sound qualities, Most typically,
daytime average levels aze close to or a few decibels less than the day-night leveh Night-time average
levels are usually 5 to IS dB less than the day-night leveh If the noise is dominated by a major highway,
the DNL is usually within one dB of the average level for the loudest hour, As with any average,
communities with very different actual noise chazacteristics can have the same day-night level.
Typical Community Sound Levels
Our world is filled with sound. People in various places have become accustomed to a wide range of
sound levels with widely varying frequency and temporal characteristics. We usually do not even notice
these background sounds. We may notice but accept certain identifiable sounds such as properly muffled
automobiles or lawn mowers. Problems occur when loud sounds regulazly interfere with activities, There
also can be annoyance when the frequency content, time pattern, information content, or concentration of
sound from a given direction makes it especially noticeable. When the sound is undesirable, we call it
noise.. Noise is by definition undesired sound.. Depending on circumstances, one person's music maybe
another's noise. Even the same sound may be music or noise to the same person at different times,
The figure on the next page shows ten minutes of sound measured for the US EPA on what is described
as a "quietsuburban street.." However, many southeastern US azeas would consider this an urban azea by
local standards, While the levelmuch of'the trine is below 50 dBA, it sometimes rises above 60 dBA. The
average level, I,EQ, forthis period is azound 58 dBA. Many people have a tendency to consider only the
quietest background sounds as the typical sound of their community. this is not realistic. A common
occurrence often overlooked is high-pitched insect sound in the range of 55 to 60 dBA. The average level
often provides a better indicator of'the sound. However, you must be cazeful. The average level can be
raised very much by a single, short, very loud sound, Thus, average levels also may not represent
conditions normally expected. Knowing the full statistical picture of the sound is helpful. The L90 indicates
the background level, azound 44 dBA ur the figure, and the LOl indicates the loudest levels, around 68
dBA in the figure,
_.. ,_ 21
Attachment 3
Environmental Sound
5
~_
:C
iE
Page 6
Timarn tnwax
y rarcra: a~roarzxs~ti^ rn~i3~ nra n
au~Et'sueu~ri~,ta srtz4~
Wlale no perfectmeasurehas been developed, the day-night levelis the best available single- number rafing
for the long term acoustical "climate" ofa community, The range ofday-night levels in American residential
communities is wide. In some wilderness and farm areas it can be below 35 dBA.. However, it is often
closer to 45 dBA due to insects, animals, and farm activities. Most residential areas are in the range of 50
to 60 dBA.. The day-night level can be as high as 85 dBA at some places in very densely populated parts
oflarge cities.
The EPA published data in 1974 relating typical day-night sound levels to population density. The data
also showed the percentage ofthe nationalurban population exposed to the various levels, The table below
is a listing of this data extended to rural areas, Some places can be noisier than expected based on the
population density alone, This can easily happen around airports and near major highways, For population
densities of 6300 people per square mile and higher, there is usually very little provision for outdoor
activities. People in these more populous areas aze more likely to live mostly indoors. They use protected
localparks or travelto recreationalareas in the country for outdoor activities, In quieter, low-density areas
there are single-family homes with lazge yards. People expect to enjoy outdoor activities in their own
yards. Thus, there is a difference between "indoor communities" that accept more noise and "outdoor
communities."
_. _.._ 22
Attachment 3
Environmental Sound Page 7
Relationship of Population Density to Sound Level
Day-Night Level, dBA % of U5 Population People per square mile (acre)
35-SO 33 Non Urban
45 9 200 (0,3) very light density
50 8 630 (1) light suburban
55 14 2000 (3) small city, suburban
60 19 6300 (10) urban multifamily
65 13 20000 (30) dense urban
70 5 63000 (100) very dense urban
The population density of southeastern US neighborhoods is usually less than that for the neighborhoods
of a large portion of the people in the United States. Consider some differences in statistics between the
LIS as whole and North Cazoliina for illustation. The population density of the 50 lazgest cities in the
country (including four with lazge rural azeas within them) averaged 4000 people per square mile in 1980.
(Not counting the four cities with large rural areas, the average is 5250 people per square mile.) By
contrast, the 17 largest incorporated cities in North Carolina averaged 2200 people per squaze mile in
1983 with the most dense having 2750 people per square mile. Forty percent of the population of the
country is concentrated in 88 counties and independent cities, none of which are in North Carolina. The
lazgest city in each state averages 13,6% ofthe state population In North Cazolina, the four largest cities
combined total only 13.1% of the population. Though these statistics make North Cazolina appear
undeveloped, this is not so. Rand McNally defines significant independent "metropolitan" azeas in its
commercial atlas. North Cazolina has sixteen "metropolitan" areas, and only six states have more. The
population and development are simply more dispersed here than in other states. Also, while the population
of this state is spread out with a low density, there are some places where sound levels are higher than
expected. These include azeas azound airports and near major highways. However, the population density
is a significant factor in consideringappropriate noise criteria for evaluating a community. Some criteria that
have been developed to evaluate noise in densely populated azeas are appropriate for the lifestyle and
expectations in-those azeas, They are not necessarily appropriate for the southeastern environment and
lifestyle.
23
Environmental Sound Page 8 /attachment 3
Effects of Noise
The scientific community has documented many effects ofnoise on people and their activities. Some are
directly related to the noise. Others aze related indvectly as a result of stress induced by the noise. The
United States EPA has recognized clear evidence that noise of sufficient intensity and duration can
Temporarily or permanently damage hearing,
Affect performance of a complicated task,
Interfere with speech and other auditory communication,
Disturb sleep, and
Be a source of annoyance,
These effects could be expected to affectthe value ofnoise-impacted property. Studies based on aircraft
noise have indicated a value reduction of .5 to 2.5% per decibel increase in average sound level for
residential properties..
The level and duration ofnoise required for hearing damage is greater thanthatrequired for other effects..
Hearing loss is razely an issue m residentialareas. Hearing losses typically occur from work or recreational
exposure to loud sounds. Heazing loss is an issue for participants and workers at the firing range.
High sound levels cause a person at work to concentrate their attenfion to their most important task. This
improves performance on simple tasks, but deteriorates it in more complicated cases where several tasks
aze done at once. Most of the research in this area has been done for sound levels over 70 dBA which
occur infrequently in residential areas.
Communications interference, sleep interference, and general annoyance effects azewell documented noise
problems in communities, These effects, especially annoyance, occur for a wide range of sounds varying
in level, frequency and temporalchazacteristics. Non-acoustical factors also strongly influence annoyance.
Stress induced by annoyance can affect the ability ofthe body to fight exisfing ailments. Annoyance, and
interferences with communication and sleep are discussed in more detail below.
Communications Interference
Most people at one time or another have experienced communication difficulty as a result of background
noise levels. The degree of interference depends on many factors. These include the level and steadiness
of the interfering noise, (particularly the level of the noise at speech frequencies), the listener's prior
knowledge or anticipation of part ofthe transmitted information, and the sound level of the transmitted
information. The sound level of the transmitted information at the listener depends on the distance between
the source and the listener. For a speaker and listener outdoors, around 6 feet apart, the beginning of
speech interference by many common steady noises is at around 60 dBA.
24
Attachment 3
Environmental Sound Page 9
Sleek Interference ~ ~ .l [
Sleep interference is a consistent and prevalent complaint in surveys taken about community noise
problems, Research reviews clearly show noise interferes with sleep either by awakening the sleeper, by
altering the depth of the sleep, or by making it difficult to go to sleep, It is accepted that steady noises of
a given level are not as disturbing as intermittent noises of that level. However, a complicating factor in
research is that meaningfulness of the noise has an effect on whether or not a person is awakened. For
instance, the cry of a baby may awaken a concerned mother but not others, Undesired sound including
information such as speech or music is difficult to ignore when one is trying to go to sleep. A developed
attitude about a noise also influences ability to go to sleep. A person upset by sound fiom a neighbor's au
conditioner may have difficulty going to sleep. However, the same person may have no problem with a
very similar sound from his own ventilation system at other times. Older people aze more likely to be
awakened, but aze less affected by the loss of sleep,
There is widespread consensus that steady sound levels in bedrooms should be below 47 dBA. Lower
levels are desirable as long as they are steady, Key factors are to prevent changes of 10 decibels or more
in sound level, or intermittent sounds over about 55 dBA. A higher level of steady sound, less than 47
dBA, can help mask intermittent sounds that would be a problem with lower steady sound levels,
Community Reaction and Annovance
The adverse responses of people to noises introduced into their environment are measured in two ways,
These are counting complaints to autlrorities or"communityreaction,"and bysurveys that rate "annoyance."
The number of complaining people does not directly indicate annoyance. Some people who aze annoyed
do not complain.. One study examined the relationship between the number of people "highly annoyed" and
the number who complained, The reseazchers found that if 1 % complained, 17% were highly annoyed,
and if 10% complained, 43% were highly annoyed. A few complaints may show a high community-
annoyancelevel.
As a result of various research studies, several important factors were identified for determining the
community reactionand annoyance produced by noise. These were identified by the US EPA as follows.
Level and frequency content of the noise.
Duration of the noise,
Time of day noise occurs,
Time of year the noise occurs,
History of prior exposure to the noise source,
Perceived attitude of the noise source owner,
25
Environmental Sound
Page 10 ,4ttaehment 3
Special characteristics of the noise that make it especially irritating,
Outdoor sound level when offending noise is not present,
People are more accepting ofnoises that occur only in daytime or only in winter, They acceptnoises they
aze accustomed to and were present when they bought their property, It helps if they believe the producer
ofthe noise is doing everything reasonable to controlit It also helps ifthe noise is notunpleasant sounding,
An important factor is whether the noise is much louder thanthe sound present in the neighborhood without
the noise. The most significant result ofthe EPA community reaction studies is thatwidespread complaints
and possibly legal action usually occur when the average level of noise from a single source is regularly
more than 5 dB above the avefage level of other sounds in the community, Vigorous community action
results for differences of 20 dB,
Perceptions are important. The attitude of'the source owner as perceived by the complainant is often the
second most important factor. Sometimes complainants have a misconception of the true attitude of the
source owner.. Other studies have identified other perception factors that are very, much related to
community reaction and annoyance, These include whether the complainant perceives the noise as
Unnecessary or unnecessarily loud,
A threat to personal health or safety,
A threat to economic investment (property value), or
Beyond his control, or if
The complainant believes he is being ignored or treated unfairly,
Special characteristics in the way the noise sounds must be considered, Some sounds are more irritating
or dif3icultto ignore than others. The acoustical designers of vehicles, appliances, and other products today
spend most oftheir effort on "sound quality." It is recognized that people not only expect quiet, but expect
a quality of sound, The most common sounds with irritating characteristics are those containing tones, or
repetitive impulses, or information content. Atone is a concentration of noise at a single frequency,
Examples of sounds with strong tones are sirens, horns, bells, whistles, and certain types of transformers,
pumps, and fans. These produce shrill, whining, or humming sounds which get attention. These aze the
types of sound that are helpful as warning devices, but are irritating to tistento continuously, A repetitive
impulsive sound is one which is made up of repeated pulses of sound. Examples are power presses,
hammering sounds, and gunshots, Such sounds usually must be several decibels quieter in measured sound
levelthan "normal" sounds to produce a s'urrilar amount ofannoyance, A five decibel penalty has often been
used, However, recent research indicates that highly impulsive sound such as gunshots must produce a
time-average level 12 dB less than more common sounds for the same annoyance. Loud or amplified
26
Attachment 3
Environmental Sound Page 11
speech and music pose difficult problems because of the information content. People do not expect to
regularly recognize music orunderstand speech coming from outside they home. Quantity of sound is the
major issue in densely populated areas. However, the quality of'sound is usually the stronger issue in less
densely populated aeeas such as much of North Carolina.
Evaluation of Environmental Sound
The normal goal in environmentalnoise evaluationand controlis to assure compatibility between the noise
in a community and the needs and expectations ofresidents and business owners. The federal government
and national standards organizations provide some guidance.. The federal govemment regulates all
transportation noise sources.. However, local governments are responsible for any regulation of local noise
sources not on public roads or in the sky. Such local regulations are usually minimal. They strive only to
prevent the worst of problems.. Regulatory compliance does not necessarily relieve a noise producer of
responsibility if the value of property impacted by the noise is reduced.
The following discusses first the general way acoustical consultants view the problem of acoustical
compatbility. There is then some specific discussion of national standards and federal guidelines. Finally,
local ordinances related to noise in residential areas are discussed, emphasizing those in North Carolina.
Acoustical Compatibility in Site Selection and Desien
Acoustical consultants aze sometimes asked to assist planners and developers in selecting sites for various
facilities and in facility design. The first goal is to find a site that is as compatible acoustically with the
intended usage as possible.. This then reduces the cost of design to maintain compatibility. The goal may
be to find a quiet location to minimize construction cost to block noise. You would not want to place a
concert hall directly in the take-off pattern of an airport, When the new usage produces sound thatwill be
difficult to control, the goalis to find a location where the sound will not be a problem. This may mean large
buffer spaces between sources and surrounding sensitve aeeas- The cost ofsound control is balanced
against the cost of providing a buffer.
Residential areas are often portrayed as especially sensitive to noise. Many communities limit noise going
into residential aeeas by ordinance. Some communities have legislation prohibiting new residential
development in especially noisy areas. In reality, the existing condifions and expectations in residential
communities vary widely. In some communities a major asset is their peace and quiet. Such communities
may be remote from city conveniences and major travel arteries. Such aeeas often attract people willing
to sacrifice some convenience for the quiet In more densely populated urban areas; the primary noise
concern is inside the home. People expect it to be noisy outdoors. They accept that as long as the sound
penetrating the home is acceptable.
--- 27
Attachment 3
Envhonmental Sound Page 12
It is widely recognized that attitudes regarding noise vary from person to person. Actually the tolerance
of a given person can vary from time to time. A young person might accept a noisier neighborhood they
can afford and that is convenient to their work or school. If they like to party, they may prefer a community
thatwillaccepttheirlafe-nightsounds, Theymaypreferaneighborhoodwithlate-night entertainment even
ifit is loud. Later in life, they may prefer a quieter place, Once they find a quiet place in the country, they
may not tolerate the same sounds they once participated in producing. Many people live in major cities
but have weekend retreats, They tolerate much more noise in the city than they would tolerate at their
weekend place. People also will accept infrequent special events much more readily than regularly
recurring events, Aloud event once ortwice a yeaz is usually not a problem ifbeneficial to the community
and well publicized, Weekly events occurring every Friday or Saturday evening aze common problems.
Many factors must be considered when evaluating compatibility between a new sound source and a
community, The fast is compliance with any applicable regulations. This may not be sufficient, Most
- regulations aze only minimally protective. Neighborhood characteristics and expectations must be
considered. Usually a sound source will affect a limited area with similaz characteristics. Sources affecting
large areas may affect several neighborhoods with different characteristics, It may then be possible to
directthe sound into areas where it is better accepted, Other sound-control measures are then considered.
Setting an appropriate goal requires judgment and experience. Most communities will accept some new
sound. If the goal is set too low, it results in extra cost for the owner of the source.. It couldjeopazdize
whether a project can be built. However, developers are cautioned against setting a high initial goal and
expecting to reduce the noise ifproblems develop. Once a problem is perceived, it often takes more noise
reduction to satisfy neighbors.
Federal Guidelines and Regulations
Most Federal noise guidelines and regulations for residential areas are based on the day-night average
sound level (DNL). However, they are inconsistent with some allowing much more noise than generally
considered desirable. These higher limits used by some agencies were set in the 1970's based on
acceptance by people who had chosen to live in such areas and by the difficulty of the agency to meet
lower noise levels, This is very misleading when new 4z increased noise is imposed on communities initially
developed with an expectation ofloiver noise. The existing population may have chosen to live in an area
because of its quiet. That would more likely be the case if'the area is developed to appeal to people
seeking a quiet environment
The U.S, Envirorunental Protection Agency in 1974 recommended that L)NI, should be kept below 55
dBA in residential areas "to protect public health and welfare with an adequate margin of safety." This level
corresponds to that normally present in a community of about 2000 people per square mile. This study,
-- 2B
Attachment 3
Environmental Sound Page 13
commonly called the "Levels Document," provided tables to help evaluate problems and potentialfornoise
complaints based on DNL, These tables were based mostly on experiences in densely populated urban
azeas, It was recognized that the measured DNL in some cases would have to be adjusted or "normalized"
before comparing to criteria to achieve an accurate assessment For instance, it was recommended that
10 dB be added to the measured DNL in a "quiet suburban or rural community (remote from Large cities
and from industrial activity and trucking.)" Unfortunately, some of the most widely applicable Federal
guidelines and regulations fail to recognize this need to tailor the criteria to the circumstances.
The U.S. Department of Housing and Urban Affairs (HiJD) has noise criteria to evaluate whether it will
fund housing in an area HUD drew upon a study by Ted Schultz relating the percentage of people highly
annoyed by noise to the DNL where they Lived. HUD recognized it desirable to set the limit at DNL 60
dBA, corresponding to noise expected m an area with a population density of about 6000 people per
square mile, However, HUD needed to build housing is more densely populated and noisier locations,
Due to economic considerations, the limit was set at a DNL of 65 dBA. This corresponds to a level
normally expected in an area of 20,000 people per square mile, Levels above DNL 65 dBA aze
considered normally unacceptable by HUD, and not a desirable condition. Due to needs for housing in
evennoisierazeas, exceptions are made.. Extra sound insulation is required for homes in the noisier areas.
Areas with DNL 60 to 65 dBA aze considered "normally acceptable," and those under DNL 60 dBA aze
"clearly acceptable,"
The Federal Aviation Administration and the Deparknent ofDefense have adopted DNL 65 as their goal
and funding for noise control. They do not recognize noise impacts from aircraft or military activities below
this. The Federal Highway Administration criterion for funding is a loudest hour of 67 dBA, This is
comparable to a DNL of 66-68 dBA in most cases. Funding can be provided in some cases for very
major noise increases that do not reach this level,
Contrasted to these are the criteria used to evaluated railroad noise by the Federal Transit Administation,
the FederalRailwayAdministrafion, and the Surface TransportationBoard.. They consider a project noise
of DNL 55,5 dBA to be an impact on an azea with an existing DNL of 55 dBA. A project with DNL of
62 dBA is considered a severe impactin such an area. In very quiet areas, transit projects with DNL 55
dBA or less can be considered a severe impact The American Public Transit Association also has a
further criteria based on maximum level during a passby, ranging from 70 dBA for single family homes in
low-density quiet areas to 80 dBA for multifamily azeas in already noisy high-density areas.
The Federal Energy Regulatory Commission regulates the noise of pipeline compression stations and
requires that they not exceed DNL 55 dBA at any pre-existing residential location.
Attachment 3 2 5
Environmental Sound
Page 14
Nafiona] Standard
The use of DNL, for land-use planning has been standardized in a national standard, ANSI S 12.9 Part 5
Sound LevelI)escriptors for DeterminationofCompatible Land Use, Note thatthis is forplanningthe use
of land with an existing noise exposwe, rather than for evaluating impact of a new noise on existing
development. An appendix to this standazd (which is notstrictly apart ofthe standaid) gives examples of
compatible day-night levels for vazious land uses, It indicates that single-family homes with extensive
outdoor use are compatible with day-night levels of 55 dBA and less, and marginally compatible in the
range of 55 to 65 dBA,
International Guidelines
The World Health Organization (WHO)has guidelines indicating that "serious annoyance" should be
expected in residential areas ifthe average sound levelexceeds 55 dBA in the daytime or45 dBA at night,
with "moderate annoyance" for levels 5 dB lower, The WHO also suggests a limit of 60 dBA on the
maximum event level at night to protect from sleep disruption.
The World Bank Group has guidelines to inswe that their projects in developing countries do not create
problems. They require that financed industrial projects not exceed average levels of 55 dBA in the
daytime and 45 dBA at night at residential locations. These recommendations are supported by the
IntemationalOrganizationforEconomic Co-operation and Development, which further recommends levels
5 dB lower in rural azeas,
><rocal Noise Ordinances
The firstknown local noise ordinance containing specific measured noise limits was adopted by Chicago
around 1955. It followed an extensive survey of existing city sounds. The limits were expressed iri
octave-bands. These were inning regulations aimed primarily at industry. Initially, they applied to steady
sounds only and were the same day and night, The equivalent A-weighted levels were 61 dBA for sound
entering other business areas; and 54 dBA for sound entering residential areas.. The survey showed that
only one percent of the industry in the city would need to act to meet the limits.
Ordinances m ay be wring performance standards for new sources, or general ordinances enforced against
any source, Zoning perforrriance standards will more commonly include octave band limits and can be
more stringent than general ordinances to limit the growth of noise. General ordinances usually aze kept
simple and based on measurements over periods typically less than an hour, They cannot be a full
assessment of the long-tens noise environment, The limits in them should be appropriate for the
measwement method and length of measwement specified. Thus, for a short measurement period, limits
should be set a little higher so as not to restrictunduly a sound that only lasts a short period, The limits also
'-- 30
Attachment 3
Environmental Sound Page 15
must consider existing accepted sounds variations in noise expectafions within the overall geographic area
covered, The limits must not be too restrictive for more densely populated aeeas that normally expect more
noise. This means that sounds that last for long periods could meet the requirements of the ordinance and
still create a problem, especially in parks of the community that expect quieter levels.
Ordinance limits are usually related to the use of the property the sound is entering. Sometimes limits are
inappropriately based solely on the use ofthe source property, More commonly, some allowance is made
for sound entering residential areas from established industrial areas. One common method is to
arithmetically average the limits for the two uses.
Many communities have adopted local ordinances for controlling noise, The U. 5.. EPA published a model
ordinance in 1975, An included survey identified 118 communites with local limits. The most popular
limns for noise entering residential areas in daytime were 55 and 60 dBA with the average being 56.75
dBA, The most popular limits for night in residential areas were 50, 45, and 55 dBA in that order,
averaging 51.75 dBA. The survey did not distinguish among maximum levels, L10, average levels or other
measures.
Some ordinances based on the Chicago model are still in effect, including measurement requirements that
cannot be met by any instrument made after 1963. Some communities have adopted ordinances limiting
specific sources to specified sound levels. At least l8 municipalities and counties in North Carolina now
have zoning or general ordinances specifying limits on sound from any source crossing boundazies. These
are summarized in the table onthe next page. L10 based on 100 measurements is the most populaz method
of measuring and setting limits in North Carolina. The most popular limits are 60 dBA in the daytime and
55 dBA at night" Most using the L10 method also specify a higher maximum level never to be exceeded.
The wider availability ofinstnunents to measutetime-average levelhas led to increasinguse ofthis measure
in new ordinances, Notice that some communities impose lower levels on sound that contains music or
speech or has tonal or repetitive impulsive chazacteristics.
Some college towns start the nightperiod later than most communities, and allow higher levels on weekend
evenings. These ordinances were originally adopted to allow fraternity parties but with some control.
These communities use maximum level limits for ease of enforcement against parties. However, the high
lunits allowed during "party hours" aze high for steady sound, and the lower limits are other times are very
restrictive for brief sounds. The ChapelHill ordinance revised'm 2001 is the most restrictive known in the
state, While not a zoning ordinance, it contains an exemption for sources existing at the time of its adoption,
requiring them to meet only the previous ordinance,
Wake County has both zoning and general ordinances. The Wake zoning ordinance sets maximum level
limits based on duration of sound, It does not make clear how this applies to a sound that varies in leveh
- _ - 31
Attachment 3
Environmental Sound Page 16
The Wake County genera] ordinance is based on L10 but requires too few measurements for reasonable
accuracy. Tt is unclear in other ways.
The City of Durham has a general ordinance thatis also referenced as a performance standard in the City-
County Zbningcode. This ordinance has an unusual requirement setting what would normally be residential
limits on all sources regardless of the neighboring property use.. Thus, a factory surrounded by other
factories still has to meet low noise limits at its boundaries, Contrasted to this is the situation in Rowan
County and the City of Greenville, There the Ihnits are set solely on the use ofthe source property so that
industrial properties only have to meet high limits even if they have residences next door. Wilmington is
unclear on this,
Community Noise Ordinances in North Cazolina, limits are A-weighted sound levels.
Community Limits for Sound into Residential Areas
From Residential From Industrial Night period, Enforcement
Day Night Day Night Measurement Tecfuuques
Apex 55 46 66 45
Limits apply ID ft from boundary, Maxunum Level limit 10 d6 higher
Boone 6D SD 6D 50
some evening 70 70 70 70
Cary 6D 60 60 60
60 dBA at night for ampli5ed sound
Chapel Hill 50 45 50 45
Also includes third-octave limits
sources extisting before 60 50
924/2001 60 50
Chatham County 60 50 60 50
Clayton 55 45 63 55
Maximum level limit ID dB higher
Cumberland Co. 60 55 60 55
Maximum level limit 15 dB higher
Davidson 70 55 70 55
Nigh[ starts I am on weekends
Durham 6D 50 6D 50
City general ordinance referenced in both city & county caning codes
Fayetteville 60 55 60 55
Max~mmn level limit I S dB higher
Also has Octave-Band Limits
Gamer 60 55 60 55
5 dB less if tonal or repetitive impulsive
Greenville 60 55 76 76
some everting 70 70
1 Opm-lam, Not specified
L10 IOD Mess, t0 sea apart
l lpm-lam, Police Pep[
Maximum Level Limits Only
9pm-gam, Police
Maximum Level Limits Only
l lpm-lam, Police Dept.
Maximum Level Limits Only-.
l ]pm-Baru
lOpm-Bum Sheriff
Maximum Level limits ordy..
l lpm-'7am, Police Dept,
LID IOOMeas. I0 sea. apart
]Opm-lam, Health Dept.
L10, Measured ova 10 mm.
1lpm-gam, Police Dept
Mexrmum Level Limits Only
11pm-Berm Uncleaz
Maximum Level L imits Only
1 Dpm-ham, Police Dept
L 1 D 120 Meas.. 5 sec. apart.
lOpm-lam, Zoning Code
Ll D 100 Meas. 10 sec. apart
I lpm-lam, Police Aept.
Maximum Level Limits Only,
32
Attachment 3
Pagel 7
Environmental Sound
Community Noise Ordinances in North Carolina, continued
Community Limits for Souod into R.esideotial Areas
From Residential From Industrial
Night period, Enforcement
Day Night Day Nght Measurement Techniques
60 55 60 55 lOpm-lam Zoning Code
Hickory Ld01DO Meas.. iD sec. apart
Lsnoir County 60 55 60 55
Maximt>m level limit 15 dB higher IOpm-ham, Sheriff
L10, Measured over 10 min.
5 dB less if mnF impulse, music, or speech,.
Raleigh 55 45 63 55
Maximum level Haut ] D dB higher llpm-lam, Poliee Dept.
LI O 1 DO Meas. 10 sec, apart
Also has third-octave limits for low-frequency music
Rowan County 60 55 75 65 l Ipm-lam Environ. Serv,
IS-20 minute avetge
55 50 55 50 I lpm-lam, Not SpeciSed
Wake County Ld 0 20 Mess, ] 0 sec. apa2
(Geaetal Ord.) 55 45 55 45 9pm-lam, Zoning Office
Wake County
(Zoning Ord.) 5 dBhigher if'less titan 20%of hour Maximum Level Limits Only
10 dB higher if less than 5% of hour
5 dB Lower if mnal or repetitive impulsive
65 55 75* 70* Ilpm-lam, Not SpeciSed
Wilmington
Max. slow limit 3 dB higher 1 minute average
* No[ clear how limits are applied across differing uses.
Note - L70 indicates that 10%of measurements must not exceed stated limit.
Attachment 4
Adopted: August 15, 1983
Amended: February 1, 1988
A RESOLUTION AND ORDINANCE TO PROVIDE FOR THE CONTROL_ OF NAISE
IN ORANGE COUNTY
Pursuant to the authority provided in N.C. Gen, Stat. Section 153A-121, 153A-
123 and 153A-133, the Board of Commissioners of Orange County hereby resolves and
ordains as follows:
Article I: Definitions
In addition to the common meaning of words, the following definitions shall be
used in interpreting this ordinance.
(1) "A" weighting scale: The sound pressure level in decibels as measured with a
sound level meter using the "A" weighted network. The standard unit notation
is dB(A).
(2) dB A : Sound level in decibels determined by the "A" weighting scale of a
standard sound level meter having characteristics defined by the American
National Standards Institute (ANSI) Publication ANSI, S14-1971,
(3) Decibel: A unit of measure on a logarithmic scale, of the ratio of the
magnitude of a particular sound pressure to a standard reference pressure,
which for purposes of this ordinance shall be 20 micronewtons/meterz,
(4) Impact Noise: Sound that occurs intermittently rather than continuously,
(5) Sound Amplifying Equipment: Any device for the amplification of the human
voice, music or any other sound, including jukeboxes, stereos and radios.
(ti) Sound Level: In decibels, a weighted sound pressure level determined by the
use of a sound level meter whose characteristics and frequency weightings
are specified in the ANSI Standards,
(7) Sound Level Meter: Any instnament certified to meet or exceed ANSI
standards which includes an omni-directional microphone, an amplifier, an
output meter and frequency weighting network(s) for the measurement of
sound level.
(8) Sound Pressure Level: In decibels 20 times the logarithm to the base 10 of
the ratio of the magnitude of a particular sound pressure to the standard
reference pressure, The standard reference pressure is 20
m i c ra n e wto n s/ m ete rz.
33
G:\Adminislrative Div\DEBRA\Ordinances\Noise\Noise Ordinance doc 1
Attachment 4
Adopted: August 15, 1983
Amended: February 1, 1988
TABLE I: Sound Levels dB(a) by Receiving Land
60 dB(A)
Sunday -Thursday 8 am - 11 pm
Friday & Saturday 8 am - 12 midnight
50 dB(A)
Sunday -Thursday 11 pm - 8 am
Friday & Saturday 12 midnight - 8 am
Article II: Maximum Permissible Standards by Receiving Land
(1) The use of sound simplifying equipment is limited to the conditions specified
in this article,
Article III: Sound Measurement Standards
Standards, instrumentation, and measurement procedures to be used in the
measurement of sound a provided for in this ordinance are as follows:
(1) Sound level measurement shall be made with sound level meter using the "A"
weighting scale set on "slow response,"
(2) Sound level meters shall be of at least Type Three meeting American
National Standards Institute, Incorporated (ANSI) S1.4 -1971 requirements
(orthe latest approved version thereof). The entire sound measurement
system shall be serviced and operated as recommended by the
manufacturer. Persons using the sound level meters shall be trained in
sound level measurement and the operation of sound level meters.
(3) Except in the case where noises are emanating from within multi-family
structures and the complainant is a resident of the same multi-family
structure, noise measurements shall betaken at the corner of the primary
structure of the complainant nearest the noise source but when this location is
not practical noise measurements shall be made at the boundary of the public
or private right-of-way which adjoins the complainants' property,
(4) In the case of noises emanating from within amulti-family structure and
where a complainant is a resident of the same multi-family structure, noise
measurements shall be made in the unit of complainant at a height of at least
four (4) feet above the floor and at a point approximately equidistant from all
walls.
G:\Administmtive Div\DEBRAIOrdinances\Noise\Noise Ordinance,doc 2
34
Attachment 4
Adopted: August 15, 1983
Amended: February 1, 1968
Article IV: Exceptions
The following are exempt from the provisions of this ordinance:
(1) Construction operations from 7 A.M. to 9 P.M. on weekdays and 8 A.M. to 9
P.M. on weekends for which building permits have been issued, or
constn~ction operations not requiring permits; provided all equipment is
operated in accordance with the manufacturers' specifications and with all
standard equipment, manufacturers' mufflers and noise reducing equipment
in use and in proper operating condition.
(2) Noises of safety signals, warning devices, emergency pressure relief valves
and church bells.
(3) Noises resulting from any authorized emergency vehicle when responding to
any emergency call or acting in time of emergency.
(4) Unamplified noises at street activity (such as fairs or parades) where the
participants have a permit for use of the streets,
(5) All noises coming from the normal operation of properly equipped aircraft (not
including scale model aircrafk).
(6) All noises coming from motor vehicles properly equipped with the
manufacturers' standard mufflers and noise reducing equipment in use and in
proper operating condition.
(7) Noise from lawful fire works and noisemakers on holidays.
(8) Lawn mowers and agricultural equipment used between daylight and 9 P.M.
when operated with all the manufacturers' standard mufflers and noise
reducing equipment in use and in proper operating condition.
(9) Agricultural equipment operated for farming purposes,
Article VI: Burden of Proof Reaarding Exceptions
In any proceeding based upon this ordinance, if an exception stated in this
ordinance would limit obligation, limit liability, or eliminate either an obligation or liability,
the person who would benefit from the application of the exception shall have the
burden of proving that the exception applies and that the terms of the exception have
been met.
35
G:V+dministrative Div\DEBRA\Ordinances\Nolse\Noise Ordinancedoc 3
Attachment 4
Adopted: August 15, 1983
Amended: February 1, 1988
Article VII: Violations and Penalties
(1) Violations
The Orange County Sheriff shall be responsible for determining noise
level violations of this ordinance, Upon his determination that the noise levels
prescribed herein have been exceeded he shall determine the source of the
noise and the person responsible for it and promptly notify the person
responsible of the noise limits prescribed herein and the fact that they are
being exceeded, He shall also then notify the person responsible to
immediately reduce the noise level to that permitted herein. Failure an the
part of the person responsible to immediately comply with the Sheriffs
directive to reduce the noise level to a permissible level after notification shall
constitute a violation of this ordinance. Failure on the part of the person
responsible to maintain the noise to a permissible level after notification shall
also constitute a violation of this ordinance, Failure to maintain noise to a
permissible level shall include any incident of noise exceeding the levels
prescribed herein occurring with twenty-four hours of notification by the
Sheriff that the noise exceeds permissible levels,
For purposes of this ordinance "The Orange County Sheriff' shall include
the Sheriff and any Deputy Sheriff of Orange County,
(2) Civil Penalties
(a) Any person violating any of the provisions of this ordinance shall be
subject to a civil penalty of one hundred dollars ($100.00), Each day of
a continuing violation shall. constitute a separate violation under this
subsection,
(b) The Orange County Board of Commissioners shall assess civil
penalties under this ordinance and shall make written demand for
payment upon the person responsible for the violation and shall set
forth in detail the violation for which the penalty has bee invoked. If
payment is not received or equitable settlement reached within sixty
(60) days after demand for payment is made, the matter shall be
referred to the County Attorney for institution of a civil action in the
name of the County in the appropriate division of the General Court of
Justice of Orange County for recovery of fhe penalty. Any sums
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Adopted: August 15, 1983
Amended: February 1, 1988
recovered shall be used to carry out the purposes and requirements of
this ordinance,
(3) Criminal Penalties
Any person who violates any provision of this ordinance shall be deemed
guilty of a misdemeanor punishable by imprisonment not to exceed thirty (30)
days or by fine not to exceed fifty ($50.00) dollars, Each day of a continuing
violation shall constitute a separate violation under this subsection.
Article VIII: Severability
If any provision of this ordinance is adjudged invalid or if the application thereof
to any person or in any circumstance is adjudged invalid, such invalidity shall not affect
the validity of this ordinance as a whole or of any part, subpart, sentence or clause
thereof not adjudged invalid,
Article XIX: Abrogation
This ordinance is not intended to repeal, abrogate or impair any greater
restrictions imposed on existing easements, covenants, or deed restrictions, Wherever
the provisions of any other law, ordinance or regulation impose higher standards than
are required by the provisions of this ordinance, the provisions of such law, ordinance or
regulation shall govern.
Article XIII: Effective Date
Fallowing the adoption of this ordinance as provided bylaw, this ordinance shall
be effective on August 15, 1983.
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