26 English
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 NRR.
EXAMPLE
1. The environmental noise level as measured at the ear is 92 decibels dB(A).
2. The NRR is 25 dB(A).
3. The level of noise entering the ear is approximately 67 dB(A).
NOISE REDUCTION RATING (NRR)
PRO-PROTECT HEARING PROTECTION
TEST FREQUENCIES(HZ) 125 250 500 1000 2000 3150 4000 6300 8000 NRR CSA Class
Mean Attenuation (dB) 18.4 22.6 30.6 38.4 32 37.8 38.8 38.9 38.3
25 B
Standard Deviation 2.9 2.2 3.0 2.6 2.9 3.9 4.2 3.4 2.6
ATTENUATION DATA | 3M PRO-PROTECT WITH STANDARD SEALING RINGS ANSI S3.19-1974
Model 90545
25
The EPA references to Federal relate to US Federal laws.
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