Reference

The NRR on every earplug and earmuff is a laboratory number, not the protection you actually get on the floor of a plant. This guide shows you how to read the NRR on the EPA label, apply the OSHA 50 percent derating rule and the NIOSH (NRR-7)/2 formula, and calculate combined attenuation when you double up earplugs and earmuffs together.

The right protector is the one a worker will actually wear all shift while still getting below 85 dBA. This guide shows you how to choose hearing protection: matching derated NRR to your noise level, comparing earplugs, earmuffs, and banded plugs, weighing comfort and communication needs, and knowing when to double up devices.

Wearing earplugs and earmuffs together is the right call above about 100 dBA, but the protection does not add up. This guide explains dual hearing protection: when OSHA and NIOSH call for it, why combined NRR is not the sum of the two devices, how to apply the +5 dB rule, and how to combine plugs and muffs correctly.