Question about NRRs

[Bullydog]

I have a question for those of who are in the know about Noise Reduction Ratings. I've been looking to get a pair of MSA electronic headphones, or even the Howard Leight featured in todays 6mmBR bulletin,p.s. Big River Tactical has them for 49.99 *every* day, not just during sales).

My question is about why they have NRRs that are so low. The NRR of the MSA's is 18, and it's 22 for the HL's. Even my el-cheapo passives have a NRR of 26. It seems to indicate that electronic ones don't block out as much noise as conventional earmuffs. However, I was wondering if maybe the NRR was defined as the *average* noise block over a given dB range, thereby lowering the ratings for the electronic earmuffs because they amplify noise up until 85dB. Is this the case, or are passive earmuffs really that much better?

 

[rijndael]

I have the ProEars ProMag Plus w/ NRR-33

http://www.pro-ears.com/shootingsportshearingprotection.htm

I'm quite happy with them. Turned off, they block more noise than my passive Peltors.

 

[ballistic64]

rijndael is right,in fact some electronic headsets have a seperate decibal setting at which time they automatically shut off,there is still some debate on if they turn off fast enough) since a gunshot is like a very quick spike.One thing to remember is that it it only takes a few decibals to double the intensity of a noise pressure level,so for example,a 20 decibal rated pressure level is over twice as intense as a 17 rated level.