§ 26-1. Definitions.

As used in this chapter, the following words and phrases shall have the meanings ascribed to them in this section:

(a)

A-weighted sound level. The sound pressure level in decibels as measured on a sound level meter using the A-weighting network. The level so read is designated dB(A).

(b)

Ambient noise. The all-encompassing noise associated with a given environment, being usually a composite of sounds from many sources near and far. Ambient noise levels are established by taking a series of observations on the adversely affected property. It is the sound level that is exceeded ninety (90) percent of the time in this set of observations.

(c)

Commercial area. As defined in the zoning ordinance of the City of Norfolk, 1968 (hereinafter "zoning ordinance").

(d)

Construction area. Any site preparation, assembly, erection, substantial repair, alteration or similar action for or of public or private rights-of-way, structures, utilities or similar property.

(e)

Decibel (dB). A unit for measuring the volume of sound, equal to twenty (20) times the logarithm to the base ten (10) of the ratio of the pressure of the sound measured to the reference pressure, which is twenty (20) micropascals (twenty (20) micronewtons per square meter).

(f)

Emergency. Any occurrence or set of circumstances involving actual or imminent physical trauma or property damage which demands immediate action.

(g)

Impulsive sound. Sound of short duration usually less than one second, with an abrupt onset and rapid decay.

(h)

Industrial area. As defined by the zoning ordinance.

(i)

Muffler or sound-dissipating device. A device for abating the sound of escaping gases of an international [internal] combustion engine.

(j)

Noise. Any sound which disturbs humans or which causes or tends to cause an adverse psychological or physiological effect on humans.

(k)

Noise control officer. Any police officer or health officer of the city responsible for the enforcement of this chapter (hereinafter "officer").

(l)

Noise sensitive zone. Any area designated by the city for the purpose of ensuring exceptional quiet. Noise-sensitive activities include, but are not limited to, operations of schools, libraries open to the public, churches, hospitals and other health care facilities.

(m)

Real property boundary. An imaginary line along the ground surface and its vertical extension, which separates the real property owned by one person from that owned by another person, but not including intrabuilding real property divisions.

(n)

Residential area. As defined in the zoning ordinance.

(o)

Sound. An oscillation in pressure, particle displacement, particle velocity or other physical parameter, in a medium with internal forces that cause compression and rarefaction of that medium. The description of sound may include any characteristics of such sound, including duration, intensity and frequency.

(p)

Sound level. The weighted sound pressure level obtained by the use of a sound level meter and frequency weighting network, such as A, B or C as specified in the American National Standards Institute specifications for sound level meters (ASA 47-1983, or a later revision thereof). If the frequency weighting employed is not indicated, the A weighting shall apply.

(q)

Sound level meter. An instrument which includes a microphone, amplifier, RMS detector, integrator or time averager, output meter and any applicable weighting network used to measure sound pressure levels.

(Ord. No. 36,406, § 1, 4-30-91; Ord. No. 41,696, § 1, 1-18-05; Ord. No. 43,426, § 1, 4-28-09)

(Ord. No. 36,406, § 1, 4-30-91; Ord. No. 41,696, § 1, 1-18-05; Ord. No. 43,426, § 1, 4-28-09)