The following terms used in this chapter, unless the context clearly indicates otherwise, shall have the respective meanings set forth in this section:
A. "Ambient noise" means the all-encompassing noise associated with a given environment, being usually a composite of sounds from many sources near and far. For the purpose of this chapter, "ambient noise level" is the level obtained when the noise level is averaged over a period of fifteen minutes without inclusion of noise from isolated identifiable sources, at the location and time of day near that at which a comparison is to be made.
B. "Ambient noise level" as referred to in this chapter, means the higher of the following:
1. Actual measured ambient noise level; or
2. Presumed ambient noise level as determined from the following chart:
Zone | Ambient Base Noise Level | |
Night (10 p.m. to 7 a.m.) | Day (7 a.m. to 10 p.m.) | |
Residential | 50 | 60 |
Commercial | 60 | 65 |
Industrial | 70 | 70 |
C. "CNEL" is the measure of the noise environment over a twenty-four hour period as defined in Title 4, Subchapter 6 of the California Administrative Code.
D. "Decibel" (Db) means a unit which denotes the ratio between two quantities which are proportional to power; the number of decibels corresponding to the ratio of two amounts of power is ten times the logarithm to the base ten of this ratio.
E. "Sound level" (noise level) in decibels is sound measured using the "A" weighting network of a sound level meter. Slow response of the sound level meter needle shall be used except where the sound is impulsive or rapidly varying in nature in which case fast response shall be used.
F. "Sound level meter" means an instrument including a microphone, an amplifier, an output meter, and frequency weighting networks for the measurement of sound levels which satisfies the pertinent requirements in American National Standards Institutes's Specification S1.4 - 1971 or the most recent revision thereof for Type S-2A general purpose sound level meters.
G. "Sound amplifying equipment" means any machine or device for the amplification of the human voice, music, or any other sound. Sound amplifying equipment does not include standard automobile radios when used and heard only by the occupants of the vehicle in which the automobile radio is installed. Sound amplifying equipment, as used in this chapter, does not include warning devices on authorized emergency vehicles or horns or other warning devices on any vehicle used only for traffic safety purposes.
(Ord. 93-04-1153 § 1; Ord. 81-8-878 § 2)