All terminology used in this chapter and not defined in this section shall be in conformance with application publications of the American National Standards Institute (ANSI) or its successor body.
A-WEIGHTED SOUND LEVEL. The sound pressure level in decibels as measured on a sound level meter using the A-weighting network. The level is designated dB(a) or dBA.
CALIBRATION CHECK. Operators of a sound level meter may certify the accuracy of meter by either witnessing the integrity seal on the meter is intact and that the device has a current certificate of calibration from an outside sound meter testing lab; or, using a sound calibrator with the meter before enforcement sampling to verify the device is functioning properly. The sound calibrator emits a test sound at specific dB level(s) to compare sound level meter readings.
DECIBEL (dB). A logarithmic and dimensionless unit of measure often used in describing the amplitude of sound.
EMERGENCY WORK. Work made necessary to restore property to a safe condition following a public calamity, work to restore public utilities or infrastructure, or work required to protect persons or property from an imminent danger.
NOISE. A sound, especially one that is loud or unpleasant or that causes disturbance.
NOISE CONTROL OFFICE. The same as the Marshalltown Police Department and shall have the responsibility of enforcing this chapter.
NOISE DISTURBANCE. Any sound which endangers the welfare, safety or health of a human being, or disturbs a reasonable person of normal sensitivities, or devalues or injures personal or real property by exceeding authorized limits.
PERSON. Any individual, association, partnership, corporation or officer thereof.
REASONABLE OPERATION. Use of construction, power tools, lawn and garden equipment with a legitimate, timely purpose that minimizes disruption to nearby persons; not used to cause annoyance or excessive disruption.
SOUND. A temporal and spatial oscillation in pressure, or other physical quantity, in a medium with internal forces that causes compression and rarefaction of that medium, and which propagates at finite speed to distant points.
SOUND LEVEL METER. An instrument which includes a microphone, amplifier, RMS detector, integrator or time average, output or display meter, and weighting networks used to measure sound pressure levels in decibels when properly calibrated or currently certified to be working correctly and the instrument is of type 2 or better, which complies with American National Standards Institute Standard 1.4-1971 or its successor.
SOUND PRESSURE. The instantaneous difference between the actual pressure and the average or barometric pressure at a given point in space, as produced by sound energy.
SOUND PRESSURE LEVEL. Twenty times the logarithm to the base ten of the ratio of the RMS sound pressure to the reference pressure of twenty (20) micronewtons per square meter (120 x 10 - 6N/m2). The sound pressure level is denoted Lp or SPL and is expressed in decibels.
(Ord. 14999, passed 7-13-2020)