Single Protection NRR

Single Protection

A common method used for single protection (either muffs or plugs) is as follows

1. Determine the laboratory-based noise attenuation provided by the HPD. This is referred to as the Noise Reduction Rating (NRR) and is listed on the packaging.
2. Subtract the NRR from the C-weighted TWA workplace noise level, as follows:Estimated Exposure (dBA) = TWA (dBC) – NRR If C-weighted noise level data is not available, A-weighted data can be used by subtracting a 7 dB correction factor from the NRR, as follows:Estimated Exposure (dBA) = TWA (dBA) – (NRR – 7)Example:TWA=100 dBA, muff NRR=19 dB Estimated Exposure = 100 – (19-7) = 88 dBA