Noise Reduction Rating (NRR).

Noise Reduction Rating (NRR). A single number noise reduction factor in decibels, determined by an empirically derived technique which takes into account performance variation of protectors in noise reducing effectiveness due to differing noise spectra, fit variability and the mean attenuation of test stimuli at the one-third octave band test frequencies.


40 CFR § 211.203

Scoping language

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