PDFWAC 296-817-30015

Use these equations when estimating full-day noise exposure from sound level measurements.

You must compute employee's full-day noise exposure by using the appropriate equations from Table 2 "Noise Dose Computation" when using a sound level meter to estimate noise dose.
Table 2
Noise Dose Computation
Description
Equation
Compute the noise dose based on several time periods of constant noise during the shift
The total noise dose over the work day, as a percentage, is given by the following equation where Cn indicates the total time of exposure at a specific noise level, and Tn indicates the reference duration for that level.
The reference duration is equal to the time of exposure to continuous noise at a specific sound level that will result in a one hundred percent dose
The reference duration, T, for sound level, L, is given in hours by the equation:
Given a noise dose as a percentage, compute the equivalent eight-hour time weighted average noise level
The equivalent eight-hour time weighted average, TWA8, is computed from the dose, D, by the equation:
[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050. WSR 15-23-086, § 296-817-30015, filed 11/17/15, effective 12/18/15. Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, and 49.17.060. WSR 03-11-060, § 296-817-30015, filed 5/19/03, effective 8/1/03.]