The adjustment applied to the manufacturer’s labeled Noise Reduction Rating (NRR) to estimate real-world attenuation. OSHA derates using (NRR – 7) / 2. NIOSH applies variable derating by protector type: 75% of NRR for earmuffs, 50% for formable earplugs, 30% for all other earplugs. Content must specify which method is applied when citing attenuation estimates.
Found this useful? Share it.
