As used in this Article, the following terms shall have the
meanings indicated:
AMBIENT NOISE
All-encompassing noise associated with a given environment.
BAND-PRESSURE LEVEL
The "band-pressure level" of a sound for a specified frequency
band is the sound-pressure level for the sound contained within the
restricted band. The reference pressure must be specified.
BEL
A unit of level when the base of a logarithm is 10, and is
restricted to levels of quantities proportional to power.
CYCLE
The complete sequence of values of a periodic quantity that
occur during a period.
DECIBEL
One-tenth of a bel, and is a unit of level when the base
of the logarithm is the tenth root of 10 and the quantities concerned
are proportional to power.
DURATION
The duration of a transient noise from a machine during the
entire period when the transient noise is first distinguished from
the ambient noise until the noise from the same machine finally recedes
into the ambient noise shall be the period of time beginning when
the transient noise first exceeds a certain band-pressure level until
it no longer exceeds the same band-pressure level, provided that it
remains above the same band-pressure level for at least 1/3 of the
total duration.
FREQUENCY
The 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.
MICROBARS
A unit of pressure commonaly used in acoustics and is equal
to one dyne per square cen-timeter.
NOISE
Any increase in the ambient noise, measured as provided in
this Article, caused by any mechanical device, including aircraft.
PERSON
Any individual, firm, association or corporation, whether
such person be the owner, lessee or charterer, his or its pilots or
copilots, as to aircraft, and any individual, firm, association and
corporation, its servants, agents or employees, as to any other sound-producing
device or mechanism.
SOUND ANALYZER
A device for measuring the bandpressure level or pressure
spectrum level of a sound as a function of frequency.
SOUND-LEVEL METER
An instrument, including a microphone, an amplifier, an output
meter and frequency-weighting networks, for the measurement of noise
and sound levels in the manner provided by this Article.
SOUND-PRESSURE LEVEL
The "sound-pressure level," in decibels, of a sound is 20
times the logarithm to the base 10 of the ratio of the pressure of
this sound to the reference pressure, which reference pressure must
be explicitly stated.
SPECTRUM
A function of time and is a description of its resolution
into components, each of different frequency, and is also used to
signify a continuous range of components usually wide in extent within
which waves have some specified characteristics such as audio-frequency
spectrum," and is also applied to functions of variables other than
time.
STEADY NOISE
Any noise having a duration in excess of one minute, and
the limits of Table II of this Article shall apply.
TRANSIENT NOISE
Any noise having a duration of one minute or less, and the
limits of Table I of this Article shall apply.
No person shall operate or cause to be operated any mechanism
or device, including but not limited to airplanes, which shall create
a noise within the Town of Hempstead exceeding the limiting noise
spectra set forth in Tables I and II, as follows:
A. Table I.
(1) Limiting noise spectrum for transient noise.
Band Pressure Level Decibels re 0.0002 Microbars
|
Octave Band Center Frequency
(cycles per second)
|
---|
92
|
63
|
87
|
125
|
79
|
250
|
72
|
500
|
66
|
1,000
|
60
|
2,000
|
54
|
4,000
|
52
|
8,000
|
(2) During the daytime from 7:00 a.m. to 7:00 p.m., the limits of Table
I hereinbefore set forth shall apply to transient noises having a
duration in excess of 12 seconds. During the night, from 7:00 p.m.
to 7:00 a.m., the same limits shall apply to transient noises having
a duration in excess of six seconds.
B. Table II.
Limiting Noise Spectrum for Steady Noise
|
---|
Band Pressure Level Decibels re 0.0002 Microbars
|
Octave Band Center Frequency
(cycles per second)
|
---|
72
|
63
|
67
|
125
|
59
|
250
|
52
|
500
|
46
|
1,000
|
40
|
2,000
|
34
|
4,000
|
32
|
8,000
|
Noise measurements and limits shall conform to the following
practices:
A. Noise shall be measured at an altitude not exceeding 100 feet above
sea level.
B. Measurements of noise emanating from any mechanism or device, including
but not limited to motor vehicles, shall be made at a distance of
at least 100 feet from the longitudinal center line of the vehicle.
C. Machinery noise originating on private property shall be measured
at the property line of the property on which the noise source is
located.