(a) Maximum Sound Levels. No operation or activity shall cause or create noise above the sound pressure levels in Tables 36 and 37, subsections (d) and (e) hereof, at the locations specified therein.
(b) Measurement. A sound level meter and associated octave band analyzer shall be employed to measure the intensity and frequency of sound. The flat network slow meter response of the sound level meter shall be used.
(c) Exemptions. The following shall be exempt from noise performance standards:
(1) Noises of construction or maintenance activities from 7:00 a.m. to 9:00 p.m.;
(2) Noises of safety signals, warning devices and emergency pressure relief valves;
(3) Transient noises of moving sources such as transportation vehicles;
(4) Noises associated with snow plowing, street sweeping and mosquito abatement;
(5) Church bells, chimes and carillons; and
(6) Other noises not under the direct control of the property user.
(d) Table 36: Permitted Sound Levels.
Preferred Center Frequency in Hertz | Maximum Permitted Sound Pressure Level in Decibels at Boundaries of Nearest Residentially Zoned Lot |
31.5 | 75 |
63 | 74 |
125 | 69 |
250 | 64 |
500 | 58 |
1,000 | 52 |
2,000 | 47 |
4,000 | 43 |
8,000 | 40 |
Above figures for octave band analyzers calibrated with Preferred Frequencies (American National Standards Institute S1.6-1960, Preferred Frequencies for Acoustical Measurement).
Sound levels above shall be modified where applicable by the adjustments in Table 37, subsection (e) hereof.
(e) Table 37: Adjustments to Permitted Sound Levels.
Adjustment in Decibels | |
(1) Duration of noise in any one-hour period (use one adjustment only): | |
A. Under 12 minutes | Add 5 dB |
B. Under 3 minutes | Add 10 dB |
C. Under 1/2 minute | Add 15 dB |
(2) At boundaries of nearest office or commercial zoned lot | Add 5 dB |
(3) Noise is impulsive in character (e.g., hammering) | Subtract 5 dB |
(4) Noise is periodic in character (e.g., hum, screech) | Subtract 5 dB |
(5) Noise may be heard between hours of 7:00 p.m. and 7:00 a.m. | Subtract 5 dB |
(Ord. 87-94. Passed 7-27-87.)