-
If you enjoy the forum please consider supporting it by signing up for a NES Membership The benefits pay for the membership many times over.
To all the guys who say to double up on hearing protection at indoor ranges
- Thread starter GunGrey
- Start date
A Guy I used to work with (Now Retired) was diagnosed with Tinnitus. He was a avid shooter & a machinist by trade.
His treatment was a induced corrective backround noise through what looked like hearing aids. Not sure if it worked or helped. I haven't seen him to ask.
Alot of people who use ear plugs are unaware they are still getting damage. There is a small bone in the back of the ear that needs to be protected. This can cause tinnitus & hearing loss.
This is a good question. I -know- empirically that there is not a genuine doubling. It's almost like there is a law of diminishing returns, but the increase in attenuation is still an order of magnitude or so.
-Mike
I used to have some info on this but can't find it at the moment. If it locate it I will post a link. The NRR does not double if you use plugs and earmuffs. If using both plugs and muffs, I believe the combined NRR provides approximately 5 decibels more than the higher rated of the two products. So if you're using plugs rated at 30 NRR and muffs rated for 27, you would end up with a total of around 35 NRR (again, I can't find the link so I could be wrong here).
Keep in mind that when using eye protection you are reducing the effectiveness of the earmuffs as they don't form a complete seal around the ears. Realistically then you're not going to get the whole +5 NRR when using both.
Thanks, I'd be interested in seeing that info.
Along that same thread, if you have foamies rated at, say, 33db, from what I'm reading, in a perfect setting there would be an insignificant difference between a pair of 25db muffs and 30db muffs? I assume that you'd get a little help than the perfect due to losses from glasses. I'm looking at buying another set of muffs (I'd like to have a spare set for guests), and I was looking at NRR30db peltors. If there won't be a significant difference between those and 25db set I have now, I might just get a second set of the cheaper pair.
HooVooLoo
NES Member
- Joined
- May 31, 2008
- Messages
- 2,514
- Likes
- 230
Well, here's the formula for determng the incoming SPL...
where the values are defined as
and the reference values for hearing threshold are: p0 = 20 µPa = 2 × 10−5 Pa and I0 = 10−12 Watt/m2
Once you figure the NR, you can work out the attenutation effects assuming a baseline attenuation factor for the type of foam, plastic and area of the device you are using to block the ear canal entrance.
Uhh...good luck!
(![[laugh2]](/xen/styles/default/xenforo/smilies.vb/014.gif "Laugh at above [laugh2]")
Acoustics is such a silly science. Silly.)
where the values are defined as
and the reference values for hearing threshold are: p0 = 20 µPa = 2 × 10−5 Pa and I0 = 10−12 Watt/m2
Once you figure the NR, you can work out the attenutation effects assuming a baseline attenuation factor for the type of foam, plastic and area of the device you are using to block the ear canal entrance.
Uhh...good luck!
(
Acoustics is such a silly science. Silly.)I'm no expert on any of this but in my opinion there is a big difference between hearing protection with a 30 NRR and hearing protection with a 25 NRR, or at least a big enough difference to justify spending the extra money for the 30 NRR. Decibels are measured in a logarithmic scale, meaning that you can't use them like ordinary numbers. For example, an increase in 3 decibels results in a doubling of the "loudness" of a sound and reducing the amount of time your ears can withstand that sound by half. So a difference of 5 NRR doesn't seem like much but in reality it is.
Holy logarithms, Batman! I'll have to read that a little more closely and see if it'll make my head explode...thanks!
I was more thinking of the difference of the 30db vs the 25db when combined with 33db foamies. I assume there'd be a difference, but the idea of foamies + muffs comes to 5db higher than the highest of the two ratings, I was wondering what the difference would be if the two ratings were only 3 apart or if they were 8 apart. If that makes ANY sense at all..
Last edited:
To answer my own question:
http://www.elvex.com/FAQ.htm#What is the effect of dual protection
We know that a 3db increase is double the sound pressure. With foamies blocking 30db and muffs blocking 30db, you'd get (in a perfect environment) an NRR of 33db, since you are blocking twice 30db worth of sound pressure. If your foamies blocked 30db, and your muffs blocked 25db, it'd be slightly less (the muffs block 17% fewer decibels, so you'd get an NRR of 32.49, assuming my math is right). If I was better at math, or wasn't at work so that I could write this all over paper, I probably could figure out what that meant in terms of difference in sound pressure.
So, yes, it makes a difference, and could be a significant one depending on ratings.
ETA: That doesn't factor in losses due to glasses and bone transfer...you'd lose some off the muffs due to glasses, and some off the foamies due to bone transfer. In any case, wearing both is better
http://www.elvex.com/FAQ.htm#What is the effect of dual protection
We know that a 3db increase is double the sound pressure. With foamies blocking 30db and muffs blocking 30db, you'd get (in a perfect environment) an NRR of 33db, since you are blocking twice 30db worth of sound pressure. If your foamies blocked 30db, and your muffs blocked 25db, it'd be slightly less (the muffs block 17% fewer decibels, so you'd get an NRR of 32.49, assuming my math is right). If I was better at math, or wasn't at work so that I could write this all over paper, I probably could figure out what that meant in terms of difference in sound pressure.
So, yes, it makes a difference, and could be a significant one depending on ratings.
ETA: That doesn't factor in losses due to glasses and bone transfer...you'd lose some off the muffs due to glasses, and some off the foamies due to bone transfer. In any case, wearing both is better
Last edited:
When looking at all these numbers, keep in mind that OSHA, the EPA, and others have realized that the NRR on the package is often wildly different than the NRR when the product is actually used. As a result they have offered a formula for de-rating the NRR listed by the manufacturer. It works out to be about a 50% reduction in the NRR listed on the packaging for foam ear plugs and about 25% for the NRR listed for earmuffs. Because of this, the EPA is currently working on new rules to use in determining the NRR for hearing protection. When the new rules/regs come out I will dump my current hearing protection and buy all new stuff if I have to. It really comes down to what you want to spend and how important your hearing is to you. I'm going to spend the extra money needed to get the highest rated protection I can.
HooVooLoo
NES Member
- Joined
- May 31, 2008
- Messages
- 2,514
- Likes
- 230
Well, Keystone, that is assuming that every manufacturer does the following...
A) Uses C-weightings for sound intensity levels, which many don't. Many use A-weighting measurements.
B) That every manufacturer uses the same NRR-reduction formula as standardized by both OSHA and NIOSH, which many don't. For example, Adjusted NRR = (Original NRR * y) – 7, where y is a percentage of the particular medium doing the attenuation. In the OSHA model, earmuffs are adjusted at -25%. Therefore, a blanket NRR for a set of earmuffs of 33 would actually work out to (33*.75) -7 = 17.75
C) Assumes that all point-source sound energy that reaches the ear is affected by the reduction in sound energy on a plane perpendicular to the point of measurement, i.e., the bones in the body. Which they don't, and which also has no bearing on how much sound intensity reaches the ear. Remember, waves propagate in a spherical pattern, not a linear one.
Here's the bottom line and the method I use, because only the human ear can determine what is "comfortable" for a person, not some impersonal audiogram...
I have an annoying dog that sits by me and barks. It makes me feel uncomfortable because it is loud. If a gunshot is the same as or louder than my dog's bark at 1 meter away when the gun fires and I am wearing hearing protection, it is not good enough. If the gunshot is softer than my dog's bark at 1 meter when the gun fires, the protection is good enough.
Advanced algebra notwithstanding.
The end.
A) Uses C-weightings for sound intensity levels, which many don't. Many use A-weighting measurements.
B) That every manufacturer uses the same NRR-reduction formula as standardized by both OSHA and NIOSH, which many don't. For example, Adjusted NRR = (Original NRR * y) – 7, where y is a percentage of the particular medium doing the attenuation. In the OSHA model, earmuffs are adjusted at -25%. Therefore, a blanket NRR for a set of earmuffs of 33 would actually work out to (33*.75) -7 = 17.75
C) Assumes that all point-source sound energy that reaches the ear is affected by the reduction in sound energy on a plane perpendicular to the point of measurement, i.e., the bones in the body. Which they don't, and which also has no bearing on how much sound intensity reaches the ear. Remember, waves propagate in a spherical pattern, not a linear one.
Here's the bottom line and the method I use, because only the human ear can determine what is "comfortable" for a person, not some impersonal audiogram...
I have an annoying dog that sits by me and barks. It makes me feel uncomfortable because it is loud. If a gunshot is the same as or louder than my dog's bark at 1 meter away when the gun fires and I am wearing hearing protection, it is not good enough. If the gunshot is softer than my dog's bark at 1 meter when the gun fires, the protection is good enough.
Advanced algebra notwithstanding.
The end.
Last edited:
It seems the best available technology is doubling up with NRR 33 muffs (like pro-ears ultra 33) and NRR 33 plugs (like Howard Leight foam) (and verifying the manufacturers' claims).
I can't find anything that suggests the compression technology of electronic muffs provides better hearing protection than the NRR of the cups themselves, rather they provide the ability to hear conversation and/or quieter sounds while shooting. (If anyone knows differently, pls let us know)
Then the next step in hearing protection is to shoot outdoors with lower caliber handguns with longer barrels, or better yet rifles.
However, with the average gunshot being around 140db, all of the above protections still leave dangerous exposure (if I'm doing my math correctly of about 100db, well over OSHA's guidelines and in the "permanent damage zone."
Sounds like there are some inventions waiting to happen.
Some links:
http://earplugstore.stores.yahoo.net/gennoisprot1.html (according to this link, the highest NRR you can get with doubling up is about 36, assuming everything is fitted and used correctly), that still leaves us exposed to > 100db
http://healthlibrary.brighamandwomens.org/RelatedItems/1,2680
http://www.e-a-r.com/pdf/hearingcons/FAQshooting.pdf
So it appears NRR 36 by doubling up is the best we can do, unless someone knows better.. maybe custom fit plugs by an audiologist?
I can't find anything that suggests the compression technology of electronic muffs provides better hearing protection than the NRR of the cups themselves, rather they provide the ability to hear conversation and/or quieter sounds while shooting. (If anyone knows differently, pls let us know)
Then the next step in hearing protection is to shoot outdoors with lower caliber handguns with longer barrels, or better yet rifles.
However, with the average gunshot being around 140db, all of the above protections still leave dangerous exposure (if I'm doing my math correctly of about 100db, well over OSHA's guidelines and in the "permanent damage zone."
Sounds like there are some inventions waiting to happen.
Some links:
http://earplugstore.stores.yahoo.net/gennoisprot1.html (according to this link, the highest NRR you can get with doubling up is about 36, assuming everything is fitted and used correctly), that still leaves us exposed to > 100db
http://healthlibrary.brighamandwomens.org/RelatedItems/1,2680
http://www.e-a-r.com/pdf/hearingcons/FAQshooting.pdf
So it appears NRR 36 by doubling up is the best we can do, unless someone knows better.. maybe custom fit plugs by an audiologist?
Unless we can convince the Mass gov't to let us purchase and use silencers...
From what I've read, a lot of the custom molded earplugs aren't as effective as the regular, shove in your ear canal and let expand, foamies. The primary advantage is that they are more comfortable for long periods.
My guess is, beyond wearing the best foamies and muffs available, the next step is to get a full helmet like the folks who do lifts in helicopters and regularly are sticking their head out the door...we can only block so much sound before the problematic transfer of sound is through your skull. While looking like a Mig pilot from Top Gun might be sweet, it's probably pretty impractical.
icyclefar
NES Member
From my own real world experience, the custom molded plugs I recently got at the Marlboro show give me a level of protection approaching deafness.
I've got 33NRR muffs, not nearly as good as the customs. I've used the 30NRR foamies, again not as good as the customs. Use them both together, still not as good as the custom molded plugs.
The maker of the customs told me I will get a TRUE 26 NRR level of protection, I believe him, and that said, I think the makers of the off the shelf stuff inflate their ratings.
I guess I could be wrong about the custom molded plugs
I may have to look into that, my previous statement about the ineffectiveness was based on things I saw while researching other types, so it could very well be flawed.I will look into the custom ear plugs. How much did they run you? An earlier post showed research suggesting to discount over the counter plugs' ratings by as much as 50%. That would make a NRR 33 really NRR 16.5, so the custom fits would be much better at a true 26NRR.
