Noise Reduction Rating - NRR 33 (When Used as Directed) Smooth, Tampered Foam for a Soft, Comfortable Fit The range of noise reduction ratings for existing hearing protectors is approximately 0 to 30 (higher numbers denote greater effectiveness) Information required BY EPA: The level of noise entering a person's ear, when a hearing protector is worn as directed, is closely approximated by the difference between the A-weighted environmental noise level and the NR Example: (1) The environmental noise level as measured at the ear is 92 dBA. (2) The NRR is 33 decibels (dB). (3) The level of noise entering the ear is approximately equal to [92 dB(A) - 33] 59 dB(A).
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