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 difference meaning is intended.
A-WEIGHTED SOUND LEVELThe sound pressure level in decibels as measured on a sound level meter using an A-weighting network. The level so read is designated dBA.
DECIBEL (dB)A unity 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 WORKA 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.
HOLIDAYFor 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 thirty-first (31st).
MUFFLERAn 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.
NOISEAny sound which annoys or disturbs humans or which causes or tends to cause an adverse psychological or physiological effect on humans.
OUTDOOR AMPLIFIED SOUNDAny 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.
PERSONAny individual, association, partnership or corporation and includes any officer, employee, department, agency or instrumentality of the United States, the State of Missouri, or any political subdivisions thereof.
SLOW RESPONSEMetering function to be used in measurement of sound for determination of enforcement of the objective noise level limits stated within this Section.
SOUNDAn 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 LEVELThe 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 METERAn ANSI standard S1.4 Type 0, I or II class instrument which includes a microphone, amplifier, RMS detector, integrator or time average, output meter and weighting network used to measure sound pressure levels.
SOUND PRESSURE LEVELTwenty (20) times the logarithms to the base 10 of the ratio of the roof mean squared (RMS) sound pressure to the reference pressure of twenty (20) micronewtons per square meter.
SOUND RECEPTORThe location or property boundary receiving noise from a sound source.
SOUND SOURCEThe location of property boundary from which a sound emanates.
TIME WEIGHED AVERAGEFor 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 fifteen-minute period, 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).