This plain-language guide covers OSHA 29 CFR 1910.95 1910.95(j) — Hearing Protector Attenuation — explaining exactly what the section requires, what it means in practice for EHS managers, and the most common compliance gaps. According to CDC/NIOSH, approximately 22 million U.S. workers are exposed to hazardous occupational noise annually. See the complete OSHA 1910.95 guide for the full standard overview.
Soundtrace delivers audiometric testing and noise monitoring that meets every 1910.95 requirement — including hearing protector attenuation — supervised by a licensed audiologist.
The Core Requirement: Adequate Attenuation
1910.95(j)(1): "Hearing protectors must attenuate employee noise exposure at least to an 8-hour time-weighted average of 90 decibels as required by paragraph (b) of this section."
1910.95(j)(2): "For employees who have experienced a standard threshold shift, hearing protectors must attenuate employee exposure to an 8-hour time-weighted average of 85 decibels or below."
This creates two different attenuation standards based on audiometric history: 90 dBA effective exposure for workers without STS, 85 dBA effective exposure for workers who have had an STS confirmed.
The NRR Derating Methods — Appendix B
OSHA Appendix B establishes three methods for calculating whether HPD attenuation is adequate:
| Method | Formula | When to Use |
|---|---|---|
| NRR with A-weighted measurements (most common) | Effective exposure = Measured TWA(A) − [(NRR − 7) ÷ 2] | When TWA is measured with A-weighting (standard dosimeter setting) |
| NRR with C-weighted measurements | Effective exposure = Measured TWA(C) − NRR | When TWA is measured with C-weighting |
| Octave band analysis | Detailed calculation using measured octave band levels and HPD attenuation at each octave | Most accurate; used when NRR method doesn't adequately account for noise spectrum |
Worked Example: NRR Derating
Worker TWA = 98 dBA (A-weighted). HPD = foam earplug, labeled NRR 33.
Effective exposure = 98 − [(33 − 7) ÷ 2] = 98 − [26 ÷ 2] = 98 − 13 = 85 dBA
This worker's NRR-calculated effective exposure is 85 dBA — adequate for a worker without STS (≤90 dBA) and just adequate for a worker with STS (≤85 dBA). However, this is an estimate using the population-average NRR. Actual individual attenuation may be significantly less if the earplug is not properly fitted.
Why Individual Fit Testing Supersedes NRR Derating
The NRR derating methods are estimates based on population-average laboratory fit data. Individual workers vary substantially in ear canal geometry, fitting technique, and achieved attenuation. A worker who achieves NRR 33 on average may achieve only NRR 15 in practice due to improper insertion, anatomical factors, or HPD style mismatch. Individual fit testing measures the actual attenuation each worker achieves and replaces the estimated NRR derating with measured data. See: HPD fit testing: complete employer guide.
OSHA 1910.95 compliant — every section covered
Soundtrace automates 1910.95 compliance across monitoring, audiometry, HPD, training, and records — with licensed audiologist supervision of the complete program.
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