§ 12.13. Noises prohibited—Decibel provisions.
(a)
Definitions. For the purposes of this Section of this Article, certain words and phrases used herein are defined as follows:
1.
Ambient noise is the all encompassing noise associated with a given environment, being usually a composite of sounds from many sources, near and far.
2.
"A" band level is the total sound level of all noise as measured with a sound level meter using the "A" weighing network The unit of measurement is the dB(A).
3.
Bel is a unit of level when the base of logarithm is ten (10). Use of the bel is restricted to levels of quantities proportional to power.
4.
Decibel is one-tenth of a bel and is a unit of level when the base of the logarithm is the tenth root of ten (10), and the quantities concerned are proportional to power.
5.
Spectrum is a function of time and is a description of its resolution into components, each of different frequency and usually of different amplitude and phase and is also used to signify continuous range of components each of different frequency and usually of different amplitude and phase and is also used to signify continuous range of components usually wide in extent within which waves have some specified characteristics such as " 1/3 octave band spectrum" and is also applied to functions of variables other than time.
6.
Sound pressure level, in decibels, of sound is twenty (20) times the logarithm to the base ten (10) of the ratio of the pressure of this sound to the reference pressure. The reference pressure is twenty (20) micropascals (20 micronewtons per square meter).
7.
Band pressure level of sound for a specified frequency band is the sound pressure level for the sound contained within the restricted band. The reference pressure is twenty (20) micropascals (20 micronewtons per square meter).
8.
Cycle is the complete sequence of values of a periodic quantity that occur during a period.
9.
Frequency of a function periodic in time is the reciprocal of the primitive period. The unit is the cycle per unit time and must be specified.
10.
Microbar is a unit of pressure commonly used in acoustics and is equal to one dyne per square centimeter.
11.
Period of a periodic quantity is the smallest increment of time for which the function repeats itself.
12.
Periodic quantity is an oscillating quantity, the values of which recur for equal increments of time.
13.
Sound-level meter is an instrument including a microphone, an amplifier, an output meter, and frequency weighting networks for the measurement of noise and sound levels in a specified manner.
14.
One-third ( 1/3 ) octave band spectrum analyzer is a device for measuring the bandpressure level or pressure spectrum level of a sound as a function of frequency.
15.
Person is any person, persons, firm, association, copartnership, joint venture, corporation or any entity public or private in nature.
16.
Emergency work is work made necessary to restore property to a safe condition following a public calamity or work required to protect persons or property from an imminent exposure to danger.
17.
All technical definitions as listed in American National Standards Institute standard S 1.1-1960 American Standard Acoustical Terminology are incorporated by reference.
18.
Differential Noise. Noise which is the result of recurring or periodic noise emission from a source that is fifteen (15) dB(A) higher than the average background sound pressure level. The frequency of the noise emission is such that it causes an objectionable nuisance noise.
19.
Impulse Sound. Sound of short duration, usually less than one second, with an abrupt onset and rapid decay. Examples of sources of impulsive sound include explosions, drop forge impacts, discharge of firearms.
(b)
General Provision: Tests for Unlawful Noise. The standards which shall be considered in determining whether a violation of Section 12.12 exists shall include, but shall not be limited to, the following:
1.
The sound pressure level of the noise.
2.
The differential sound pressure level compared to the average sound pressure level of the noise.
3.
Whether the sound is normally present for the current land usage and zoning.
4.
Whether the noise source is controllable or is under the control of a person or business.
5.
The sound pressure level of the background noise if any.
6.
The nature and zoning of the area within which the noise emanates.
7.
The density of the population of the area within which the noise emanates.
8.
The time of the day or night the noise occurs.
9.
The duration of the noise.
10.
Whether the noise is recurrent, intermittent or constant.
11.
Whether the noise is produced by a commercial or noncommercial activity.
(c)
Classification of Use Districts Residential, Manufacturing, Commercial. It shall be unlawful to project a sound or noise excluding noise emanating from cars, trucks or motorcycles from one property to another, within the boundary of a use district which exceeds either the limiting noise spectra set forth in Table I below, or exceeds the ambient noise level by more than three decibels.
1.
Sound or noise projecting from one use district, into another use district with a different noise level limit, shall not exceed the limits of the district into which the noise is projected.
2.
Measurement of noise. (A) The measurement of sound or noise shall be made with a sound level meter and octave band analyzer meeting the standards prescribed by the American National Standards Institute (ANSI S1.13 Rev.), Methods for the Measurement of Sound Pressure Levels. The instruments shall be maintained in calibration and good working order. Octave band corrections may be employed in meeting the response specification. The sound measuring instrument shall be calibrated prior to and following measurement of noise conducted for the purposed of enforcement of these regulations. This calibration shall be documented. Measurements recorded shall be taken so as to provide a proper representation of the noise source. The microphone during measurement shall be positioned so as not to create any unnatural enhancement or diminution of the measured noise. A windscreen for the microphone shall be used when required. Traffic, aircraft and other transportation noise sources and other background noises shall not be considered in taking measurements except where such background noise interferes with the primary noise being measured. The calibration source instrument shall be sent for calibration to the manufacturer on an annual basis.
(B)
Sound pressure level measurements shall be made using a Type II sound level meter set to the "db(A) Slow" scale. The person assessing the sound level shall record the maximum recorded level, the minimum recorded level and the average level for the recording period. The sound pressure level readings as measured by these instruments shall be compared to the noise level standards as listed in Table I below and adjusted for the time period of measurement. Sound pressure level measurements that exceed the values in this table shall be deemed to be a violation of these standards.
TABLE I
Maximum Average Sound Pressure Levels For Use DistrictsUse District
Residential Commercial Manufacturing TIME* (mins) Day Night Day Night Day Night 60 <50 <45 <65 <60 <75 <70 30 50 45 65 60 75 70 15 55 50 70 65 80 75 5 60 55 75 70 85 80 1 65 60 80 75 90 85 Maximum Peak 75 70 85 80 95 90 * Sound pressure levels between these time periods shall be linearly interpolated and not interpreted as a step function. Sound pressure level measurements can also be made using a third octave band analyzer or filter set on a Type II grade or better sound pressure level instrument. This instrument shall also be set on the db(A) scale and calibrated to a standard traceable to the (NBS) NIST.
1/3 Octave band sound pressure level readings as measured by these instruments shall be compared to the noise level standards as listed in Table II below and adjusted for the time period of measurement. Sound pressure level measurements that exceed the values in this table shall be deemed to be a violation of these standards.
(C)
The measurement shall be made at the property line of the property on which such noise is generated, or perceived, as appropriate, five feet above ground.
(D)
In the case of an elevated or directional sound or noise source—compliance with the noise limits is to be maintained at any elevation at the boundary.
3.
The limits hereinabove referred to shall be in accordance with the following table:
TABLE II
Maximum Permissible Octave Band Noise Levels For Use DistrictsUse District
Residential Commercial Manufacturing Octave Band
Center Frequency
(Hertz)Day Night Day Night Day Night 31.5 72 63 72 63 75 69 63 71 61 71 61 74 67 125 65 55 65 55 69 62 250 57 47 57 47 64 54 500 51 40 51 40 58 47 1000 45 35 45 35 52 41 2000 39 30 39 30 47 36 4000 34 25 34 25 43 32 8000 32 25 32 25 40 32 Special Characteristic Noises Impulsive Noise: (hammering etc.): minus 5 db from Table I. Periodic Noise: (mechanical hum screech, etc.): minus 5 db from Table I.
Predominant Frequency Noise: (harmonics, limited frequency band noise, etc.): minus 8 db from Table II.
Differential Noise: Differential noise is limited to a maximum of 15 dB(A) above average sound pressure level.
4.
Day is defined as the time period from 7:00 a.m. to 10:00 p.m. Night is defined as 10.01 p.m. to 6.99 a.m.(decimal time).
TABLE III
Type of Operation in Character of Noise
(Correction in Decibels)Noise source operated less than 20% of any one-hour period; plus 5*.
Noise source operated less than 5% of any one-hour period; plus 10*.
Noise source operated less than 1% of any one-hour period: plus 15*.
Noise of impulsive character (hammering, etc.): minus 5.
Noise of periodic character (hum, screech, etc.): minus 5.
* Apply one of these corrections only.
5.
Sound pressure levels shall not exceed the night limits on Sundays and holidays.
(d)
Motorized Vehicles. It shall be unlawful to operate a motorized vehicle within the city limits which creates a noise or sound which exceeds the noise level limits set out in Table IV below:
TABLE IV
Limiting Noise Levels for Motor Vehicles(a)
Trucks and buses:
Over 10,000 pounds:
87 dB(A) measured at 50 feet-Maximum Allowable Limit
93 dB(A) measured at 25 feet-Maximum Allowable Limit
Under 10,000 pounds:
80 dB(A) measured at 50 feet-Maximum Allowable Limit
86 dB(A) measured at 25 feet-Maximum Allowable Limit
(b)
Passenger cars:
78 dB(A) measured at 50 feet-Maximum Allow-able Limit
84 dB(A) measured at 25 feet-Maximum Allow-able Limit
(c)
Motorcycles, including other vehicles:
87 dB(A) measured at 50 feet-Maximum Allow-able Limit
93 dB(A) measured at 25 feet-Maximum Allow-able Limit
Measurement of Noise. Sound pressure level measurements shall be made using a Type II sound level meter set to the "db(A) Slow" scale. The person assessing the sound level shall record the maximum recorded level, the minimum recorded level and the average level for the recording period according to the American National Standards Institute (ANSI S1.13 Rev.), Methods for the Measurement of Sound Pressure Levels.
The sound measuring instrument shall be calibrated prior to and following measurement of noise conducted for the purposes of enforcement of these regulations. This calibration shall be documented.
The sound pressure level readings as measured by these instruments shall be compared to the noise level standards as listed in Table III above. Sound pressure level measurements that exceed the values in this table shall be deemed to be a violation of these standards.
(e)
Enclosed Places of Public Entertainment. 1. It shall be unlawful to sustain in any enclosed place of public entertainment including but not limited to a restaurant, bar, cafe, discotheque, dance hall, any amplitude equal to or in excess of 95 dB(A) sustained for more than 30 seconds, unless there is posted in a conspicuous location within such establishment a sign with wording as follows:
Noise levels in this establishment may exceed 95 dB(A) (decibels). Long-term exposure to noise levels at or above this level can result in hearing loss.
(2)
Measurement of Noise. Sound pressure level measurements shall be made using a Type II sound level meter set to the "db(A) Slow" scale. The person assessing the sound level shall record the maximum recorded level, the minimum recorded level and the average level for the recording period according to the American National Standards Institute (ANSI S1.13 Rev.), Methods for the Measurement of Sound Pressure Levels.
The sound measuring instrument shall be calibrated prior to and following measurement of noise conducted for the purposes of enforcement of these regulations. This calibration shall be documented.
The sound pressure level readings as measured by these instruments in excess of 95 dB(A) for more than a 30 second averaging period shall be deemed to be a violation of these standards.
(f)
Exemptions. The following uses and activities shall be exempt from noise level regulations: (1) Noises of safety signals, warning devices, and emergency pressure relief valves.
(2)
Noises resulting from any authorized emergency vehicle, when responding to an emergency call or acting in time of emergency.
(3)
Noises resulting from emergency work as defined in Section 12.13(a) 16.
(4)
Any other noise resulting from activities of a temporary duration permitted by law and for which a license or permit therefore has been granted by the city in accordance with Section 12.13(g).
(5)
Any aircraft operated in conformity with, or pursuant with, federal law, federal air regulations, and air traffic control instruction used pursuant to and within the duly adopted federal air regulations shall be exempt from the provisions of Section 12.13(f) as well as the other regulations of this ordinance. Any aircraft operating under technical difficulties, in any kind of distress, under emergency orders of air traffic control or being operated pursuant to and subsequent to the declaration of an emergency under federal air regulations shall also be exempt from the provisions of Section 12.13(f) as well as the other regulations of this ordinance.
(g)
Application for Special Permit. Applications for a permit for relief from the noise level designated in this ordinance on the basis of undue hardship may be made to the City Manager or his designee. Any permit granted by the City Manager hereunder shall contain all conditions upon which said permit has been granted and shall specify a reasonable time that the permit shall be effective. The City Manager, or his designee, may grant the relief as applied for if he finds:
(1)
That additional time is necessary for the applicant to alter or modify his activity or operation to comply with this ordinance; or
(2)
That the activity, operation or noise source will be of temporary duration, and cannot be done in a manner that would comply with other subsections of this section;
(3)
That no other reasonable alternative is available to the applicant.
The City Manager may prescribe any conditions or requirements he deems necessary to minimize adverse effects upon the community or the surrounding neighborhood.