Most guidelines agree that sound levels in excess of 85 decibels (dB) can damage the sensory cells in the inner ear, and there is a dosage guideline for this: at 85 dB a safe exposure would be 8 hours. How much is 85 dB? Stand next to your dryer or garbage disposal at home – that’s about 85 dB.
If the decibel level (loudness level) increases by 3 dB – cut the exposure time in half. For example, if safe exposure time is 8 hours at 85 dB, safe exposure at 88 dB goes down to 4 hours. So by the time 100 dB is reached, we’re talking about very little exposure time, indeed.
…and this is for causing measurable hearing loss – there is strong evidence now that “hidden” hearing loss, can occur with lesser exposures. “Hidden”, here, refers to damage to the auditory system that does not show up with a conventional hearing test or screening. To be safe with our hearing, we recommend using earplugs or earmuffs with any exposure at or above 80 dB. If you have to raise your voice louder than your normal level for conversation to be heard, you are likely in noise levels louder than 80 dB.
When you consider the sound levels coming out of the barrel of a shotgun or rifle and the safe levels we just discussed, you can see – there is no safe level for firearms without hearing protection. The rule is simple: If you want to keep from damaging your hearing and experiencing the disabling effects of permanent hearing loss, use hearing protection any time you use power-tools, mowers, leaf-blowers, firearms and any noise that would cause you speak above your normal level to be heard.