PDA

View Full Version : Electronic Hearing Protection, Some Health-Related Thoughts (long)


Double Naught Spy
December 10, 2001, 08:53 AM
"Electronic hearing protection" is a really cool product, but does it actually do anything to really provide you with better protection? I believe the answer is NO, but there are some great benefits to electronic muffs or even electronic plus (of which I know little about), but it does not appear that protection of one's hearing is really a benefit over manual models of protection.

This is based on my own consumer research into the topic. I am not an expert and if an audiologist is out there and can verify or refute anything I have said, that is great. If someone has specifics on the actual hearing protection models indicating my information is incorrect, I would like to know as well. I am hopeful that if I have erred in any of this, that it is on the conservative, safer side.

This is for those of you who may not have considered the topic in this manner, in part, because some of the information is not clear and the terms are a little misleading, this may be interesting if you are interesting if proper hearing protection.

As far as I have learned, the "electronic hearing protection" under the $200 price range is not electronic hearing protection per se, but manual hearing protection with electronic sound amplification. This allows you to maintain normal conversations because the amplification actually defeats the manual noise protection of the muffs. The benefit is that the electronics cut off this conversation benefit before noises like gun shots are amplified and deafen you painfully. Here is the rub. The best "electronic hearing protection" at $200 does not protect you nearly as well as the best manual hearing protection at $30 (Leightning).

For many rifles, it may not matter so much, but the best of the electronic hearing protection is rated around 20-24 db reduction. There is some that is less as I recall, around 15-20. A lot of your cheaper normal muffs only reduce around 15-20 db. For rifles, that might be okay due to how the sound is projected away, but probably not for handguns or not bigger bore rifles or if you are not the shooter of the rifle and so the sound is not projected away from you as much as it is for the shooter.

One of the truely nice things about the electronic muffs is that you can wear plugs and muffs (sometimes called double plugging) and be so much better to your ears and still hear conversations. With double plugging with electronic muffs, you may lose the leaves crunching under your feet that electronic muffs alone would provide you (mentioned as very cool in another thread on electronic muffs), but since hearing damage is cumulative, not hearing leaves under your feet when you are out blasting cans, targets, IDPA, or whatever certainly may be better than not hearing leaves crunch under your feet for the last 20 years of your life.

Most people are never aware they are losing their hearing until they start becoming dysfunctional in conversations and noisy environments and by that time, it is far too late. Here is an example based purely on hypothetical numbers to illustrate how little hearing you could be losing, not realizing it, and then not realizing the cumulative effect until many years later. I do not suggest these numbers represent reality and from what I have read, they are quite likely conservate unless you always had adequate (good) hearing protection in all the noisy environments of your life.

Say you wear your 15 db noise reduction, ultra slim, nothing is lighter or more sexy manual muff hearing protection and it works properly. You always have. If you lose 1/2500th of what should be your normal hearing every time you shoot, an amount you could not actually perceive, and you shoot 25 times per year (once every two weeks not including vacation), 10 years of shooting will mean you have lost 10% of your hearing. By age 50, if you shoot your entire adult life, you have lost 1/3 of your ability and that means you lose out on hearing much of the cooing of your grandchildren, crunching leaves, and even the guy with squeaky shoes who snuck in your house in the middle of the night. This is just the hearing loss from shooting alone, not including what you did to yourself in the army, listening to stereos, racing cars, etc. For comparison, you could have lost that much doing a single tour in 'Nam as an artilleryman and not realized how bad off you were until after you got back stateside.

Outddoors, double plugging also may not be as big of a deal as in doors where sound pressure is actually extended in time because you get the initial pressure wave of sound, but several of its reflections of walls and floors and some will impact you simultaneously. However, being safer is rarely a bad idea, indoors or out.

On the db scale, every 3 db increase is actual a doubling of sound pressure. Muffs with a protection level of 24 are twice as good as muffs at 21. Muffs rated at 30 are NOT twice as good as muffs rated at 15 in reducing noise pressure, but 32 times better.

Personally, I find it much easier to talk with plugs in and no muffs than muffs and not plugs, even when the plugs are rated higher. This can be an issue when you want good hearing protection from shooting, but want to chat between sets. People tend to pull off and forget muffs. Many pluggers just leave the plugs in I have noticed. Why?

Well, muffs are actually better sound reducers than plugs, regardless of the ratings. Part of the reason is because of sound conduction through aural structures (not the auditory canal) and through the bone of your head. Plugs do little to stop conduction of sound vibrations. Muffs preclude a lot more of it. Another part of the reason is that muffs actually cover the ears sound collection capabilities and slight leakage of sound has minimal effect. Fits of any commercial, non-custom product will have some leakage, some less than others. For muffs, the seal to the head is imperfect due to hair and things like glasses arms. For plugs, they must be absolutely seated correctly. Plugs do not prevent sound collection, but block collected sound from the auditory channel. A slight leak of sound due to a plug not inserted properly can still be significant. Double plugging helps assure there is no significant leakage even if neither are 100%. Also, plugs mean you can maintain hearing protection even when you take of muffs.

The only times I have experienced unprotected gun booms is when I took off my protection. I wore muffs exclusively then. Unfortunately, most electronic muff users I see are concerned with wasting batteries and so they are constantly turning off and on their muffs and when not on electronically, often take them off their heads. The result at gun ranges and classes is that they get caught by the same booms as everyone else with non-electronic muffs.

So, with really loud guns and especially indoors, I suggest wearing plugs and muffs (electronic or not). Remember that electronic muffs (that most of us might be able to afford) do not electronically offer more sound protection than their units do as muffs alone and most electronic muffs are rated well below the best non-electronic muffs in noise reduction, such as Leightning with a reduction of 31, at least 4 times better pressure reduction than any electronic protection I have seen (and someone correct me is there is a better reducing electronic rated at better than 25).

So, until technology changes (assuming I am not behind the curve on knowing it changed already), electronic hearing protection is only as good as the manual hearing protection of the muffs alone, electronics off, for hearing protection purposes - which is why you wear the protection, right?. For convenience, satety of hearing range commands, etc., electronic muffs of infinitely better than standard manual hearing protection muffs, no doubt.

Current, reasonable priced products appear to be only manual hearing protection with the huge benefit of non-damagine sound amplifation.

PS - If there is a product out that actually out there now that is no bigger than the Leightning (31 db protection model, which are actually not small by any stretch) provides 30+ db reduction, stereo sound amplification, I do have my $200 and want to buy them now.

fastforty
December 11, 2001, 01:36 AM
A well thought & worded read, thanx.

I've got a closet full of on&off brand muffs that *claim* anywhere rom 21-29 db noise reduction. None of them hold a candle to my Peltors, which only claim 19 db. The amplifiers are just an added bonus :)

Jaywalker
December 15, 2001, 06:08 PM
This is a well-reasoned explanation - I'm sorry I read it a week or so after Double Naught Spy posted it. I expect electronic protection for Christmas (since I selected the model, the url, and helpfully left the printout on my wife's pillow). I will double-plug. A belated thanks!

You wouldn't by any chance had done the same kind of research on shooting glasses, perhaps?

Jaywalker

C.R.Sam
December 15, 2001, 09:09 PM
Very well thunk out Probably few audiologists could have done better.

Sam

Archer1440
December 16, 2001, 08:00 PM
Interesting stuff. I wear my Peltors outdoors, and double-plug indoors. I also have my hearing checked about every 6 months due to occasional on the job exposure to SPL's over 100 DB.

No significant non age related degradation in 10 years.

Double Naught Spy
December 20, 2001, 03:32 PM
When I first started looking into "electronic hearing protection," I was under the impression that maybe it was the type used in industry (few places) that is actually a form of noise cancellation technology where sound waves entering the microphone are used to generate exact opposite sound waves in order to cancel the sound. That type of electronics are especially useful in applications where there is low tone loud noise such as generated by aircraft engines.

Apparently, such noise protection has not been adapted for shooting, yet. So, I was surprised to find out that electronic hearing protection for shooters wasn't electronic at all, but manual passive.

Sorry to be so wordy. Typing (with typos) comes easy to me.

dZ
December 23, 2001, 01:08 AM
Peltors are a boost amplifier with a frequency triggered attenuation circut
19 db is a pretty good reduction

being able to easily communicate with the guys on the line cut my stress level

cutting stress preserves hearing

Double Naught Spy
December 23, 2001, 10:04 AM
An NRR of 19 dB is okay, but not good at all. The benefits of the electronic muffs is being able to hear things going on that you would not normally hear with the muffs on. However, the noise reduction really should be more than 19 dB.

According to the stuff I have read, damage to the ear occurs around levels as small as 120 dB. That is actually fairly loud and can be the start of being painful. Depending on the model, barrel lenght, caliber, load, etc., most firearms will produce sounds significantly louder that may range from 130-170 dB.

If the gun you shoot is producing 150 dB of sound and you are wearing muffs or plugs rated at 19 dB reduction, then the net impact on your ears will still be 131 dB, well into the range for causing damage.

Here is a neat article from Field and Stream that might be of interest to many of you.

http://www.fieldandstream.com/hunting/gunsbowsammo/ol/hearing.html

The Tac 6s by Peltor are fine electronic muffs, but the shooter should wear plugs with the muffs. Peltor notes on their higher rated Tac 7s that the 25 dB protection is such that shooters don't need to double plug. I think they are "deaf wrong" on that.

slickpuppy
December 24, 2001, 05:42 AM
Unfortunately the article did not provide enough information on the frequency spectrum of blast. It was mentioned in passing. If anyone has that kind of information please pass it on to us!

The reason I bring this up is that almost all of the electronic hearing protectors give a general/average type of NRR. Wolf Ears, on their website, provides a chart showing the NRR across the frequency spectrum.

I purchased a set of the Wolf Ears and they are pretty effective. Still, I double plug.
http://www.derry.gentexcorp.com/1030a.html
is the site. The pdf file they have shows the NRR. Just click on the blue Wolf Ears lettering.
These are also used quite a bit by aviation folks. If you ever do much flying in little planes you will appreciate these.

Thanks for the links DNS!

Jaywalker
December 24, 2001, 10:06 AM
Double Naught Spy, that is a fantastic article. It's shortened for publication, but it sounds like credible work. Maybe the frequencies slickpuppy mentions are in the report that's availible for $10. I'd also be interested in knowing the theoretical reason that decibels measured in a tradition manner proved unreliable.

I expect to get electronic hearing protectors as a gift, and now will always double plug. After reading that article, however, I'm wondering about that approach. With the good e-ear protectors rated at 19 - 21 db reduction, and foam at 6, that makes a total of 25 to 27. I wonder if that's enough.

Jaywalker

Tman
December 24, 2001, 03:45 PM
I have a set of Peltor 7S muffs and find them "ok", but was wondering if anybody knew of higher rated electronic muffs. The regular Leightning's (non-electronic) are rated at 31 NRR but I can't hear when people are talking. Anybody know of higher rated electronic muffs?

9x45
December 24, 2001, 10:43 PM
I have been shooting competitively for over 30 years, and electronic hearing protection is the best thing to come along since Glocks! I have worn out, or broken, 3 sets of Peltor Tactical 6 models. When you shoot like I do, around 1,200 - 1,500 rounds a month, Peltors are excellent. And the really big plus? You can hear your buddies talking "SHET" about you on the line....

slickpuppy
December 25, 2001, 01:27 PM
From the Gentex website and their Adobe Acrobat (.pdf) file the Wolf Ears have the following frequency attenuation characteristics, ie, how much sound in the particular frequencies are reduced:

8KHz - 35.8db
6KHz - 35.8db
4KHz - 35.5db
3KHz - 33.6db
2KHz - 31.5db
1KHz - 31.0db
500Hz - 26.1db
250Hz - 26.4db
125Hz - 22.9db

I would really like to see how the other electronic muffs attenuate across the frequency spectrum.,

Tman
December 25, 2001, 08:49 PM
The wolf ear stats you are listing, are these the "ear plugs" or "hearing aid" design or are these the electronic muffs? Those stats look pretty good. I'm always on the lookout for the ultimate electronic muffs.

slickpuppy
December 25, 2001, 10:20 PM
tman,
Those are the electronic muffs that I posted on. I have a pair of those and they work ok. As I mentioned previously, I still double plug with the EARS plugs that have around 31 db of attenuation as well when I am under cover or indoors.

As you can see from the attenuation data I posted, the lower frequencies are substantially less in the attenuation capabilities of these muffs. I am not an audio engineer, so I would be interested in seeing audio types post some additional information regarding this impact on hearing and what the audio spectrum is with respect to blast.

As an electrical engineer and computer scientist I am very interested in this topic. If others can post additional information I would certainly be interested in seeing it!

Please post your data!

slickpuppy
December 25, 2001, 10:47 PM
....

Jaywalker
December 25, 2001, 11:39 PM
slickpuppy, have you tried the $10 report that the Carmichaels' article was based on? It's likely the frequencies are mentioned there.

BTW, I did receive Peltor Dimension 1 e-hearing protectors today, along with Silencio Disposable Soft Foam Earplugs. Surprisingly, the foam plugs list an NRR of 29, significantly higher than this thread has led me to expect. I wonder if this has anything to do with bone conduction.

FYI, they assume an environmental noise level of 92dBA, with the following attenuation characteristics for the foam ear plugs:

Freq (Hz)________Mean Attenuation (dB)
125______________30.6
250______________36.0
500______________37.9
1000_____________35.5
2000_____________36.9
3150_____________42.8
4000_____________43.6
6300_____________46.7
8000_____________45.8

Jaywalker

Edited to clarify that the attenuation figures quoted refer to Silencio's claim for the foam earplugs.

slickpuppy
December 26, 2001, 04:48 AM
JW,
I haven't purchased the report. I was hoping one of our board audio engineers might purchase it and enlighten us as to the content.

Are those attenuation figures for the foam plugs or your muffs?

I believe the attenuation figures for the Wolf Ears were with 84db of environmental noise. Do you think Peltor may be using a higher environmental noise floor to get higher attenuation numbers on paper maybe?

I usually use the EARS brand foam plugs. They have many varieties available. Here is the product page on their plugs:
http://www.aearo.com/html/products/hearing/prod01.htm
On that page, right hand side, you can click on the attenuation data and see how their different products perform.

Here is their home page:
http://www.aearo.com/
They own the Peltor brand now, apparently.

Another thing I did after the start of this thread is to take an old beater pair of David Clark muffs I've had for over 20 years and put the foam from them in my Wolf Ears. My usual daily range visit got cancelled due to the holidays, unfortunately, so I couldn't check them out.

Jaywalker
December 26, 2001, 08:51 AM
Do you think Peltor may be using a higher environmental noise floor to get higher attenuation numbers on paper maybe?
It would likely have that effect, but possibly Silencio is producing protection for high-noise areas that don't quite reach the level requiring hard-shell protection.

I also have several sets of beater ear protectors, whose foam and ear seals are clearly collapsed. My Peltor Owner's Manual has a couple of interesting quotes. First, "The special soft Sealing Rings provide a complete seal around the ear...they also serve to limit damaging impluse 'bone transmitted vibrations' caused by loud sounds." Second, "...after an extended period of use the Sealing Rings should be replaced... (with) the separate 'Maintenance Kit.'" Together, these imply that I either replace the old beater ear seals or replace the entire unit.

Jaywalker

johnbt
December 26, 2001, 02:04 PM
My hearing is shot due to tinnitus, and I guess I'm on the road to hearing aids. My father uses two and my uncle one and we have no one to blame but ourselves for not using hearing protection in the '50s and the 60s. (Although my dad could blame the Army Air Corps and WWII, I guess.)

I currently use good plugs and Bullseye-10 muffs(-29 IIRC) and have no plans to change to anything that will let more sound in.

I have always wondered about the small-print disclaimer on the back of the muff packages. The last one I looked at was Peltor and it said something to the effect that the db numbers DON'T APPLY TO GUNFIRE.

Could it be that all the attenuation numbers by frequency are only for sustained noises and not for impulse noise such as gunfire?

Having said all that, bigger is better. And double-plugged is better yet.

John

slickpuppy
December 26, 2001, 05:11 PM
johnbt,
That disclaimer is not on my Wolf Ears.

Just a WAG here, but I would think that gun fire is across the frequency spectrum, including audible and inaudible frequencies. Also, that would indicate the muff response time to impulse noise is a bit lacking.

I am not an audiologist or physician so I can not answer the most logical question of "What is the typical response time of the human ear to noise/impulse noise?"

I would hope that manufacturers marketing their devices for gun monkeys would test using noise generators duplicating gun fire instead of white noise generators or some such.

Of course hope and them doing are unknown to me. The testing techniques are really the most important thing to analyze to see if they truly match real world conditions.

Tman
December 30, 2001, 10:44 PM
I just started adding ear plugs to my Peltor 7s electronic muffs because of this thread. I noticed a significant decrease in the intensity of gunfire at the indoor range, yet with my muffs turned up a little higher, I still was easily able to hear the range master. Combo of ear plugs plus electronic muffs gets a definite thumbs up from me. Wish I had done it sooner.

Double Naught Spy
January 2, 2002, 04:26 PM
Tman, good for you! That really is the best way to go in order to be able to hear what is going on around you without sacrificing your hearing.

part swede
January 3, 2002, 10:35 PM
I wear custom-molded plugs I bought at a hearing aid center for $50. One day they took rubber casts of my ear canals and two weeks later I picked them up. I also wear muffs and a polyethylene pith helmet which clamps the muffs down hard, and (in theory) helps deflect some noise from my skull. With all this, indoor range fire still sounds like a hammer hitting an anvil nearby. So does a high-power rifle at an outdoor range. But it's not painful like an earlier time when I was wearing foam plugs and muffs near someone shooting .40's.