TWAeq Calculated from Percent Dose (NIOSH)

This calculates the 8-hour time-weighted average equivalent sound level (TWAeq) from a noise dosimeter's percent dose reading using the NIOSH criterion. The NIOSH criterion uses a 3 dB exchange rate (doubling rate) with an 85 dBA criterion level and 140 dBA ceiling.

Note: For OSHA calculations using a 5 dB exchange rate with a 90 dBA criterion level, use 16.61 instead of 10 in the formula and 90 instead of 85.

Formula (NIOSH)

  • \( TWA_{eq} = 10 \log_{10}(D/100) + 85 \text{ dBA} \)

Formula (OSHA)

  • \( TWA_{eq} = 16.61 \log_{10}(D/100) + 90 \text{ dBA} \)
Variable Description
TWAeq 8-hour time-weighted average equivalent sound level (dBA)
D Percent dose (%) from noise dosimeter

TWAeq Calculated from Percent Dose (NIOSH)

\( TWA_{eq} = 10 \log_{10}(D/100) + 85 \text{ dBA} \)
TWAeq
dBA = 10 * Log10(
D
/ 100) + 85

Digits of Precision:

%