Mission Statement
Lexicon of Noise Parameters and Terminology



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General & Technical Data





PWL = Lw = Acoustic Watts = Sound Power Level; Re: 10-12 Watts
SPL = Lp = Sound Pressure Level % Pr; Re:20 micropascals (20-Pa)
dB = Decibel = 10 log10 (Px / Pr)2 = 20 log10 (Px / Pr)
Hz = Hertz = Frequency = cycles per second
1/1-Octave or 1/3-Octave = most common frequency groupings
dBA = Decibel, A-weighted = Units of EPA & OSHA audible criteria
TWA = Time weighted average of dBA (exchange rate dependent: Q)
dBG = Decibel, G-weighted = Units of Infrasound criteria (low freq.)
LEQ = Equivalent continuous SPL or PWL (time integrated; Q=3)
TL = Transmission Loss = static figure of merit by 1/1 or 1/3-bands: dB
IL = Insertion Loss = dynamic figure of merit by 1/1 or 1/3-bands: dB
STC = Sound Transmission Class = single figure of merit for TL in
speech frequencies (should not be used for mechanical equipment)
NR = Noise Reduction = figure of merit for SPL reduction = Lp1 - Lp2
NC = Noise Criteria = architectural criteria for occupied spaces
NRC = Noise Reduction Coefficient = arithmetic mean of absorption coefficients from 250-Hz to 2.0-kHz, rounded to nearest +/- 0.05

Copyright 2010 Aeroacoustic Engineering Consultants, LLC
Last modified: March 03, 2011