Definitions. All words used in this Section
not defined below shall be in conformance with applicable publication
of the American National Standards Institute (ANSI) or its successor
body for the purpose of this Section. The following words and phrases
are defined and shall be construed as defined below unless it shall
be apparent from the context that a different meaning is intended.
A-WEIGHTED SOUND LEVEL
The sound pressure level in decibels as measured on a sound
level meter using an A-weighting network. The level so read is designated
dBA.
AMBIENT NOISE LEVEL
The A-weighted sound pressure level of all the encompassing
noise associated with a given environment, being usually a composite
of sounds from many sources.
DECIBEL (dB)
A unit for describing the amplitude of sound, equal to twenty
(20) times the logarithm to the base 10 of the ratio of the pressure
of the sound measured to the reference pressure, which is twenty (20)
micronewtons per square meter.
EMERGENCY WORK
A work performed for the purpose of preventing or alleviating
physical trauma or property damage threatened or caused by an existing
or imminent peril. Emergency work may also be declared by the City
as outlined above.
HOLIDAY
For the purposes of this Section, the following days will
be recognized as holidays for the purpose of granting permits to exceed
maximum sound level: Memorial Day, Independence Day, Labor Day and
December 31.
MUFFLER
An apparatus consisting of a series of chambers or baffle
plates designed for the purpose of transmitting gases while significantly
reducing sound emanating from such apparatus.
NOISE
Any sound which annoys or disturbs humans or which causes
or tends to cause an adverse psychological or physiological effect
on humans.
OUTDOOR AMPLIFIED SOUND
Any sound using sound equipment, whose source is outside
or whose source is inside and the sound propagates to the outside
through open doors or windows or other openings in the building.
PERSON
Any individual, association, partnership or corporation and
including any officer, employee, department, agency or instrumentality
of the United States, the State of Missouri or any political subdivisions
thereof.
SLOW RESPONSE
Metering function to be used in measurement of sound for
determination of enforcement of the objective noise level limits stated
within this Section.
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 resulting in
air pressure variations perceptible by the human ear. The description
of sound may include any characteristic of such sound, including duration,
intensity and frequency.
SOUND LEVEL
The unweighted ("flat") or weighted sound pressure level
obtained by the use of a sound level meter and frequency weighting
network, such A, B or C as specified in the American National Standards
Institute specifications for sound level meters (ANSI S1.4). If the
frequency weighting employed is not indicated, the A-weighting shall
apply.
SOUND LEVEL METER
Any instrument including a microphone, an amplifier, an output
meter and frequency weighting networks for the measurement of sound
pressure levels in a specified manner which complies with Type 2 of
better standards established in the ANSI S1.4-1971 "Specification
for Sound Level Meters".
SOUND PRESSURE LEVEL
Twenty (20) times the logarithms to the base 10 of the ratio
of the roof mean squared (DBMS) sound pressure to the reference pressure
of twenty (20) micronewtons per square meter.
SOUND RECEPTOR
The location or property boundary receiving noise from a
sound source.
SOUND SOURCE
The location of property boundary from which a sound emanates.
TIME WEIGHED AVERAGE
For the purposes of enforcement of the allowable noise level
limits in this Section, sound level measurements shall be average
when possible and appropriate over a two (2), eight (8) or fifteen
(15) minute period. The measurement can be manual or by using a sound
level meter which includes an ANSI standard integration feature. The
proper designation for sound level measurements made using this technique
is dBA Leq (Equivalent Level).
ZONING DISTRICT
Districts established by the zoning ordinances of this City and found in Chapter
405 of the St. Peters City Code.