Section R. 325.2404 - Definitions pertaining to noiseRule 4. As used in these rules:
(a) "Auditory protective equipment" means ear plugs, muffs, or other protective devices worn by an exposed person to attenuate airborne noise pressure in the ear canal.(b) "Broad-band noise" means noise generally distributed throughout the sound frequency spectrum.(c) "Continuous noise" means an uninterrupted noise or more than 60 noises per minute.(d) "dBA" means the airborne sound pressure level measured with the "A" weighting network of a sound level meter.(e) "Decibel" or "dB" means a dimensionless unit expressing the ratio of 2 sound quantities in logarithmic form, 1 of which quantities is a reference level of 0.0002 microbar.(f) "Impact noise meter" means an instrument used for the measurement of peak sound pressures of impulse.(g) "Impulse noise" means a single noise or 60 or less noises per minute.(h) "Noise" means airborne sound in the frequency range from 20 to 20,000 hertz or cycles per second.(i) "Sound level meter" means an instrument, whose characteristics comply with those specified in the American standards association, standard SI.4-1961, used for the measurement of the airborne sound pressure level.Mich. Admin. Code R. 325.2404