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Understanding Noise Reduction Ratings
Formula
The Noise Reduction Rating (NRR) on hearing protection labels does not equal the actual noise reduction you receive. OSHA recommends derating the NRR: subtract 7 and divide by 2 for the real-world reduction.
Noise above 85 dB can cause hearing damage. OSHA limits exposure to 85 dB for 8 hours, with halving for every 3 dB increase (88 dB = 4 hours, 91 dB = 2 hours, etc.).
Common use cases:
- Selecting adequate hearing protection
- Calculating safe work exposure times
- Meeting OSHA workplace safety requirements
Frequently Asked Questions
Maria Gonzalez
Registered Dietitian, RD, MPH
Maria is a Registered Dietitian with a Master's in Public Health. She focuses on evidence-based nutrition assessment tools including BMI, calorie calculations, and body composition analysis.
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