For the purpose of this subchapter, the following definitions shall apply unless the context clearly indicates or requires a different meaning.
NOISE LEVEL REDUCTION (NLR). Difference in noise level from outside to inside of the building. NLR is a difference, in decibels, between A-weighted sound levels; it depends primarily on the nature of the walls, ceilings, windows, doors and vents and, to a lesser extent, on the amount of sound-absorbing material in the room in which the sound is received. It shall be measured, if so required by the building official, in a completed and furnished building by application of the testing procedure described in this amendment.
QUALIFIED ARCHITECT OR ENGINEER. An architect or engineer registered in the state who, by reason of this training and experience, is considered qualified to pass judgement on acoustical design, materials, and methods of construction for the attenuation of noise. The qualification of the architect or engineer relative to acoustical design must be submitted to and found to be acceptable by the building official.
SOUND ABSORPTION. Capacity of the materials and furnishings in a habitable room to absorb sound.
SOUND LEVEL. In decibels, the quantity measured by an instrument that satisfies American National Standard Specification for Sound Level Meters, S1.4-1971, or the most recent revision thereof. Sound level is understood to be measured with the A-weighted filter and slow response of the instrument.
SOUND TRANSMISSION CLASS (STC) OF A PARTITION. A singlefigure rating of the sound-isolating properties of a partition, which takes into account the relative importance of the sound transmission loss of the partition at different frequencies. The determination of the sound transmission class of a partition is described in “Determination of Sound Transmission Class,” American Society for Testing and Materials, Designation E413-73.
SOUND TRANSMISSION LOSS OF A PARTITION. A measure of the sound-isolating properties of a wall, floor, ceiling, window or door, that is characteristic of the partition itself and not the room of which it is a part. The determination of sound transmission loss of a partition, in the field, is described in “Measurement of Airborne Sound Isolation in Buildings,” American Society for Testing and Materials, Designation E336-71 or the latest revision thereof.
('80 Code, § 7-43) (Ord. 1857, passed 7-18-79)