denton
Member
That's true. I use my shooting muffs when I'm running my table saw or my snow blower. Open your mouth, and the volume increases. And that points out a limit to both ear plugs and muffs: When you reach a point that you are getting most of the sound through your mouth or through bone conduction, there is no point in adding more attenuation at the ears. That seems to happen around 30-35 dB.
As pointed out, dB are logarithmic. 10 dB is a factor of 10, 20 dB is a factor of 100, and 30 dB is a factor of 1,000 in sound pressure level. 3 dB is very close to being a factor of 2.
So cheap earmuffs that attenuate 23 dB reduce the sound pressure level by a factor of about 200. Harbor Freight sells a pair rated at 33 dB, which is a factor of 2,000. That's quite a difference. 23 dB muffs are very inadequate. A rifle muzzle blast is around 150 dB at 1 meter, so 33 dB muffs get you down to 117 dB. That's still a lot.