Hearing Protection

American Work Safety provides disposable and reusable earplugs, rated in Noise Reduction Rating or NRR. An NRR of 20 dB, for example, would reduce the sound of a typical chainsaw (around 100 dB) to approximately 80 dB (the volume of a ringing telephone) under ideal circumstances.

OSHA recommends that hearing protection be worn under any circumstances where you are exposed to 100 dB or more, and recommends a maximum expoure time of 8 hours for 90 dB, 4 hours for 95 dB, 2 hours for 100 dB, 1 hour for 105 dB, 30 minutes for 110 dB, and 15 minutes for 115 dB.

Each 3 dB represents an effective doubling in sound pressure (or protection); using NRR 20 dB earplugs with NRR 20 dB earmuffs would provide a total effective NRR of 23 dB.