I have a set of ~$10 ear muffs that cut most of the noise but let me hear the voice frequencies just fine. I keep them at work for when I have to spend a lot of time around the air compressor. Anything over about
25dB reduction is good. For the utmost protection that I know of, get a pair of 29dB ear muffs and use earplugs, too. It gets bloody awful quiet in there ... you can hear your pulse and breathing over anything coming from the outside.Bill