All words used in this Article 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 Article.
The following words and phrases are defined and shall be construed
as defined below unless it shall be apparent from the context that
a difference 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.
CODE ENFORCEMENT OFFICER
The Code Enforcement Officer of the City of Dardenne Prairie
or his duly authorized representative.
DECIBEL (DB)
A unit for describing the amplitude 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) 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 Article, 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 Article.
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 SI.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 SI.4-1971 "Specification
for Sound Level Meters."
SOUND PRESSURE LEVEL
Twenty (20) times the logarithms to the base ten (10) of
the ratio of the roof mean squared (RMS) 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 Article, sound level measurements shall be average
when possible and appropriate over a two-, eight-, or fifteen-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.
It shall be unlawful for any person to create or assist in creating,
permitting, continuing or permit the continuance of any loud, disturbing
or unnecessary noise in the City. Noise of such character, intensity
and duration as to be detrimental to the life or health of any individual
or to unreasonably disturb or annoy the quiet, comfort or repose of
any individual is prohibited. Noises which are the result of legally
operating businesses engaged in their normal operations are subject
to the objective noise level limits listed in this Article.
Any condition detrimental to the public health, safety, morals
or welfare and in violation of this Article is declared to be a public
nuisance, and it shall be unlawful for any person, including the owner
or occupant of any premises within the boundaries of the City and
within one-half (1/2) mile of the boundaries thereof, to maintain
or permit to be maintained such public nuisance.