Can you answer a question re ear plugs for me?

[FoghornLeghorn]

I asked an audiologist yesterday, but she didn't know.

I always thought the NRR on a pack of ear plugs meant that was how much they reduced the noise.

Then I read that to determine the true noise reducing effect, one subtracts seven from the NRR and divides by two.

http://www.coopersafety.com/noisereduction.aspx

That means if my plugs have a NRR of 27-7/2=10. So if I'm firing a weapon = 169dB and only wearing earplugs, the noise hitting my ears is 159dB. That's still well above the instant damage level. Even wearing muffs, you only add 5dB to the protection which still equates to instant damage.

Is this accurate, because if it is, it's no wonder so many shooters have to yell at each other.

Oh, and the audiologist determined that I have mild hearing damage in my left ear and mild to moderate in my right. Dunno exactly what to blame. Loud music. Construction equipment. Bird hunting.

 

[wogpotter]

I think that NRR is more a marketing thing than a scientific measurement. I usually try to find the dB reduction as its a direct measurement & so not subject to manipulation. Unfortunately many are measured for continuous sound levels, that means they are pretty much useless for sudden pulsed noise like gunshots.

 

[F. Guffey]

Is this accurate, because if it is, it's no wonder so many shooters have to yell at each other.

Could be a difficult bad habit to change, they are so used to hollering at each other on the Internet, music? Loud is rude and damaging to the ability to hear.

F. Guffey

 

[sixguns]

I use the same ear plug we use at work (Boeing Aircraft) Moldex 33 NRR. If there are other shooters at the range I may put my headset on too.

Bird hunting without hearing protection is painful to my ears even from hunters 1 or 2 hundred yards away.

 

[FoghornLeghorn]

Bird hunting without hearing protection is painful to my ears even from hunters 1 or 2 hundred yards away.

I suffer from tinnitus and have for many years. I attribute it to bird hunting as back in the day, we didn't really have hearing protection. Cotton maybe. The filter off a cigarette maybe.

But things like dove hunting where there are a lot of birds and a lot of hunters. If only I knew then what I know now.......

 

[Onward Allusion]

I suffer from tinnitus but have always worn plugs or muffs. Sometimes both. I've always wonder how I got tinnitus, but your calculation/explanation makes a lot of sense because I use to shoot on the average 3 times a week INDOORS.

 

[FoghornLeghorn]

I suffer from tinnitus but have always worn plugs or muffs. Sometimes both. I've always wonder how I got tinnitus, but your calculation/explanation makes a lot of sense because I use to shoot on the average 3 times a week INDOORS

I think you should read this thread:

http://thefiringline.com/forums/showthread.php?t=200072


Particularly this sentence:

Shoot with other people and you have to add all the rounds shot cumulatively (10 people shoot 100 rounds and everybody's done for the day; toss a handcannon or 30 cal rifle in and you're back down to 200 rounds cumulative).

 

[MountainMike]

Bad math from Cooper website?

Interesting subject, but I think the Cooper website [http://www.coopersafety.com/noisereduction.aspx] you provided a link to is a little over the top on this subject.

I'm not a mathematician, but dividing by two seems to defy (my) logic.

According to the OSHA website [https://www.osha.gov/dts/osta/otm/noise/hcp/attenuation_estimation.html] yes, subtract seven (7) from the NRR and let that be your dB attenuation because of a probably less than perfect fit and truly uncalibrated work noise levels. Notice the use of "A weighted" versus "C weighted" dB levels in their equations.

Further down their page, OSHA does SUGGEST reducing the calculated NRR by 50% (divide by two) to be on the "safe side", seemingly from an uncalibrated work noise level and/or poor workplace fit of the protectors.

Why have a NRR in dB if there are so many possible "exceptions" to the general rules?

 

[wogpotter]

Which makes no sense as OSHA & in particular MOSH (MD's version) You must test & document the testing & calibration of the Decibel meter on an annual basis.
Even if you just think that possibly maybe you might be even close to the OSHA/MOSH defined "noisy environment" criteria.