Greetings all-
I was following this thread with some interest as hearing protecting is very important to me.
I too am interested in electronic hearing pro but it is a bit expensive for me at this time and Il lbe issued the Peltors when I deploy.
Ive used the foam earplugs and issue triple flanges we all recieve from the Army or see on the range. And I use a pair of civilian passive muffs that are rated 31 NNR when shooting on my own.
Ive looked at all the above mentioned products, ones Ive used, and the OSHA stats on hearing protection and thought I'd post some interesting factoids:
OSHA forumla for rating hearing pro
X= dBA - NNR - 7
X = dBC - NRR
So with an estimated dBA of 150 for a gunshot using the Sordins rated at NNR 18 dB that would be 139 = 150 - [18 - 7]. So thats still a large amount of dB to be exposed to. Occupational hazard I suppose.
Because NRR are determined in controlled labratory environments OSHA recommended adjustment for work place conditions subtracts 50% from that figure so you would end up with only about an NNR of 6.
X = 150dBA - [(NNR - 7) x 50%] would be a dBA of 144 which is still within the realm of pain and injury when exposed to the sound of a larger caibre gunshot.
Someting else I found intersting was their rating for double protection. They only ad an NRR of 5 for the second protection device worn which would be
X = 150dBA - [(NRR-7) x %50] + 5. That would bring the dBA to 139 which is far higher than the dBA90 recommended by OSHA and touted by most manufactorers of hearing protection.
http://www.osha.gov/dts/osta/otm/noi...stimation.html we can take OSHA with a grain of salt of course but withoug looking CDC and other sources its the only thing I have at this time. EPA ratings for NRR go back to 1981 BTW.
If Ive misinterpreted this information somebody please sqaure me away!
Some NRR ratings for hearing pro:
Sordin 18dBA
Peltor 21dBA
Surefire EP4 19dBA
Combat Plugs (Green-Yellow) 22dBA/25dBA
Hex Foam 29dBA
Triple Flange Issue 26 dBA
Round Yellow Foam 19-28 dBA fit depending