what? WHAT???


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BugOut
November 5, 2012, 11:42 AM
:confused: can someone please explain the ratings used for ear plugs? It was my understanding that the higher the NNR (noise reduction rating), the more protection is offered the wearer. At the range last week, I was told (quite rudely), that I was miss informed. :confused:

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holdencm9
November 5, 2012, 11:50 AM
I am pretty sure that is how it works. That's why el cheapo ear muffs are always rated for a measly 24 or something, but quality muffs or plugs are in the 30's.

I do know, if you double up on plugs and muffs, they don't double the reduction, it is like 2/3 of the combined NRR.

mdauben
November 5, 2012, 11:52 AM
Whoever told you that was not only rude, they were wrong. :rolleyes:

While the scale isn't linear (doubling the NRR does not double the protection) any increase in the NRR is definetly an increase in protection.

Ryanxia
November 5, 2012, 11:57 AM
In the future you'll have better luck getting knowledgeable responses if you have a more descriptive title.

hso
November 5, 2012, 12:00 PM
Whoever told you that was not only rude, they were wrong.

Exactly correct.

NRR, and SNR, are the values for noise protection. They indicate the decibels of noise attenuated by properly applied hearing protection. An NRR 30 ear plug will attenuate 30 dB of noise when properly inserted. An NRR 33 ear plug with attenuate 33 dB of noise when properly inserted.


While there is a move towards using SNR for technical reasons the rules are still that NRR or SNR value tells the user how much noise properly applied hearing protection devices will provide to the user.

One of the details about applying muffs over plugs (assuming both are properly used) is that you can't add the values directly (NRR 30 plug + NRR 30 = 35 dB of protection and not 60). This has to do with the aforementioned logarithmic nature of the power of sound and the protection provided.

oneounceload
November 5, 2012, 12:00 PM
Another issue, especially with the foam insertable plugs, is that their rated reduction only applies IF the plugs are inserted as the maker says - that is ALL the way in the ear. Way too many barely have them inserted so their noise level is higher. For high pressure rounds, you need both in the ear protection and muffs for around the ear to protect the mastoid area surrounding your ear

Reloadron
November 5, 2012, 12:06 PM
Give this a read. (http://www.coopersafety.com/NoiseReduction.aspx) Without getting into db and the non-linear functions you were correct.

Noise Reduction Rating (NRR) is the measurement, in decibels, of how well a hearing protector reduces noise as specified by the Environmental Protection Agency. The higher the NRR number the greater the noise reduction.

Whoever told you that you were misinformed is misinformed themselves. Also, if they were to tell you that you were misinformed I would think they would correctly inform you. Meaning explain their thinking. Read the link as it is informative.

Ron

JohnBT
November 5, 2012, 12:27 PM
Speaking of how they fit, here are the 1999 NIOSH recommendations for estimating the true NRR if 'subject fit' is not addressed.

www.elvex.com/facts06.htm

"NIOSH, Criteria for a Recommended Standard, Occupational Noise Exposure, June 1999: NIOSH recommends that Subject Fit data in accordance with ANSI S12.6-1997 be used. (To our knowledge no U.S. manufacturer has made "Subject fit" test data available). NIOSH recommends the following de-rating of hearing protector NRR’s, if subject fit data is not available.

Earmuffs, Subtract 25% from the manufacturer’s labeled NRR
Formable earplugs, Subtract 50% from the manufacturer’s labeled NRR
All other earplugs, Subtract 70% from the manufacturer’s labeled NRR
The above de-ratings apply only when the noise measurement was made with a dB(C) scale. When only a dB(A) scale measurement is available, the de-rated NRR’s should be reduced by seven dB. Observe that earmuffs require the lowest de-rating."

holdencm9
November 5, 2012, 12:45 PM
"...Observe that earmuffs require the lowest de-rating."

Yes, that makes intuitive sense, because they are the most fool-proof.

Squeeze them in your hand for awhile to warm them up, roll tightly between fingers, pull back ear, insert plug all the way, hold it in for at least 30 seconds until plug is fully expanded.

vs

Put on head. Like headphones. :)

Sav .250
November 5, 2012, 01:00 PM
I wear "eye-muffs." Don`t know the rating and don`t care. Reason being, they are really good . I`ve been next to guys firing some big "cannons"
at the range and the noise level is non-intrusive. Just like it should be.

JustinJ
November 5, 2012, 01:01 PM
On a side note, for very loud firearms ear plugs are not really sufficient. Sound waves can actually enter and damage the ear from behind the ear lobes as well. Frequency of the noise can also be a factor. The best protection is quality ear plugs and ear muffs.

nazshooter
November 5, 2012, 05:12 PM
Justin & Oncecloud: Thanks for pointing that out about adding muffs to ear plugs. I knew people did that but didn't know the mechanics of why. Is there any generally accepted idea of what calibers require both or at least what sound level could be damaging without adding muffs?

tcj
November 5, 2012, 06:25 PM
While we're on the subject, any recommendations on electronic, low-profile muffs?

abq87120
November 5, 2012, 09:56 PM
Get these. Best deal in hearing protection:

http://www.opticsplanet.com/howard-leight-impact-sound-management-electronic-hearing-proctection-earmuffs-r01526.html


I occasionally see them for a little under $50. Go ahead and get them now. For the few bucks, it's not worth the wait.

barnbwt
November 5, 2012, 10:03 PM
On a side note, for very loud firearms ear plugs are not really sufficient. Sound waves can actually enter and damage the ear from behind the ear lobes as well. Frequency of the noise can also be a factor. The best protection is quality ear plugs and ear muffs.


Bingo! Double up, ya'll! I'm actually tempted to bring a dang mouthguard to the range sometime in case one of you guys sidles up to me with a braked/compensated whatever-magnum. .223s in particular are "tuned" to the frequency of one of my molars (*ow*).

With a pistol, I can unclench my jaw to isolate it, but on a rifle, it's a tad harder; and quite a bit of energy can get transmitted up through your teeth to your ears if you clench them. If you don't believe me, open your mouth at the range sometime, and you'll see how much noise your lips cut out.

Safety is silly, but so are the decibels we're producing with these things :cool:

TCB

holdencm9
November 5, 2012, 10:03 PM
abq,

Thanks for the recommendation. I have been casually shopping around for electronic earmuffs for awhile. May finally pull the trigger.

They are $45 at amazon (http://www.amazon.com/Howard-Leight-R-01526-Electronic-Earmuff/dp/B001T7QJ9O/ref=sr_1_1?ie=UTF8&qid=1352167272&sr=8-1&keywords=howard+leight+impact+sport+electronic+earmuffs), and the reviews there seem to echo your. I am going to go ahead and order.

Ehtereon11B
November 5, 2012, 11:06 PM
NRR stands for Noise Reduction Rating. The number displayed is in decibels which is a measure of sound energy. For example a 12ga shotgun blast is about 165 dB, a dial tone on the phone is about 80 dB and a normal conversation is about 60-65 dB.

The NRR is a rating of how many decibels are reduced when being worn. So if you are shooting a 165 dB shotgun with 30 NRR earplugs, you hear 125 dB. Simple math. 125 dB is the generally accepted threshold of ear pain.

barnbwt
November 6, 2012, 08:34 PM
I would take any Noise Reduction Rating number with a grain of salt. Last time I looked into the details (when I got into shooting) there was no real standard for testing. Yeah, it reduces decibels by that number, but on average, on median, at best? And most importantly which frequencies were damped at what level? Depending on your caliber, the typical means of protection may be ineffective, due to poorer damping at low frequencies (big bores) or high frequencies (small bore magnums).

I prefer to go with what feels like it is reducing the concussion and noise levels (across the spectrum) the best; silicone earplugs with tight muffs atop them.

TCB

Shadow 7D
November 6, 2012, 08:59 PM
As some have mentioned there are a two main ways to transmitting sound, the ear drum and bone,

if you want to do something funny, put on your ear protection, then open your mouth wide, you will hear much better.

also, when dealing with pressure (db) the hard plastic of the muff, helps to reflect a bit of the way, and works on DIFFERENT frequencies, than the ear plug, another reason to use both.

BugOut
November 15, 2012, 11:05 AM
I think the "dumb ass" at the range was trying to sell what he had. Plain and simple. Thanks to all for the "sound advise". :)

BP Hunter
November 15, 2012, 12:49 PM
I still think empty 9mm casings still work best. Ask Gunny himself.:D

230RN
November 15, 2012, 01:43 PM
Anyone have a clue about how wearing eyeglasses (or other eye protection) under the muffs affects the effectiveness?

I don't wear the regular range goggles since I have industrial eyeglasses with thin temples, but it seems to me the wide temples on the goggles would be kinda "leaky" under the muffs.

Terry, 230RN

Reloadron
November 15, 2012, 06:44 PM
Anyone have a clue about how wearing eyeglasses (or other eye protection) under the muffs affects the effectiveness?

I don't wear the regular range goggles since I have industrial eyeglasses with thin temples, but it seems to me the wide temples on the goggles would be kinda "leaky" under the muffs.

Terry, 230RN
Interesting thing about hearing protection. Go to the range and put the ears on. Then while shooting is going on gently press the ears closer to your ears. Notice a decrease in the sound levels? Regardless of the numbers hearing protection is only as good as the fit. While hearing protection with a poor fit will attenuate the sound a good fit with a good seal around the ears is imperative.

Ron

Safetychain
November 15, 2012, 07:42 PM
Reloadron, I fully agree that pressing the earmuffs against the head will better the fit but just putting the palms of your hands on the hard shell of the earmuffs reduces the surface area of the hard shell to the outside which will increase the attenuation in addition to dampening the vibration of the hard shell. I use a cheap pair of Harbor Freight electronic muffs (with a cuttout at 70-80 db) in addition to plugs. I am sure the $15 muffs are not nearly as good as a pair of $100 muffs but I am satisfied. A snap of the fingers or clapping of the hands will activate the shunting circuit and with the volume turned high, you can carry on a conversation and hear the range commands easily through the plugs.

Reloadron
November 15, 2012, 08:06 PM
Reloadron, I fully agree that pressing the earmuffs against the head will better the fit but just putting the palms of your hands on the hard shell of the earmuffs reduces the surface area of the hard shell to the outside which will increase the attenuation in addition to dampening the vibration of the hard shell. I use a cheap pair of Harbor Freight electronic muffs (with a cuttout at 70-80 db) in addition to plugs. I am sure the $15 muffs are not nearly as good as a pair of $100 muffs but I am satisfied. A snap of the fingers or clapping of the hands will activate the shunting circuit and with the volume turned high, you can carry on a conversation and hear the range commands easily through the plugs.
Absolutely! The newer electronic muffs are great. Have to love those things. :)

My only point was in my opinion the fit of hearing protection is important. When on the range we know what is too loud as shots are fired. The noise level should be comfortable and when that is achieved, we are good to go. Really matters not if the hearing protection is $15 Harbor Freight or a set of $100 super duper acoustical hearing protection. We know when loud is too loud.

Ron

denton
November 16, 2012, 12:37 AM
then open your mouth wide, you will hear much better

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.

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