I am posting this in GD because I think it touches on some broader issues, and might possibly generate some more discussion. There have been some suppressor testing results published over in the suppressors forum, and it is interesting to see how the numbers compare. The results in this test were done with Buel & Kjaer sound measurement equipment.

First, some background...

Some of you may know that I am an Ear Nose and Throat doc. Practicing in Texas, I see quite a few people every month with noise-related hearing loss due to firearms use –– usually over the course of many years. Some of this is due to just not using hearing protection in their youth, but we are also seeing quite a few individuals with hearing losses who do use hearing protection regularly. This was confirmed by a recent study in 2009 where they looked at police officers using BOTH muffs and earplugs over a ten year period and found that they experienced hearing deterioration related to long-term shooting even with the protection. [1]

There is an interesting article this month in the official ENT specialty Journal "Otolaryngology Head and Neck Surgery" comparing the effectiveness of ear level (muffs and plugs) suppression versus muzzle level protection (suppressors) for several popular rifle and pistol calibers. The full article can be found at the link below, however, most will not be able to access it unless you have institutional access or a subscription, so I thought I would summarize some of the findings because people here may find it relevant.

Abstract and full article:
Comparison of Muzzle Suppression and Ear-Level Hearing Protection in Firearm Use, Branch, Otolaryngol Head Neck Surg 2011;144:950-953

The Cliff Notes version is that Dr. Branch makes an excellent case that suppressors are vastly superior to ear muffs/plugs and really the only things capable of making certain firearms hearing safe. He also gives some excellent real world data on the "real life" sound attenuation by various devices as opposed to what is printed on the package.

More background:

The “safe” exposure level for impulse noises like gunshots is set by OSHA at 140dB. On the packaging, hearing protection devices like muffs and plugs will have a published Noise Reduction Ratio (NRR) which represents the amount of sound that will be attenuated when used properly.  As a basic reference, on average, pistol and rifle sound will generate between 152 to 165 dB of impulse sound, so that tells you that you need to have about 25 dB of REAL NRR to be safe.  

Unfortunately, NRR numbers are derived from lab data with continuous sound rather than impulse noise like gunshots and it is well known that the published numbers vastly overestimate the level of real world protection. Here is a chart for reference that some of you may have seen before:



Original Source [2]

As you can see, hearing protection devices (especially ear plugs) vastly underperform their advertised levels. The average level of real world sound attenuation with the ear plugs is only around 5dB and only around 8-10dB for ear muffs. Even best case scenario, using foam plugs with a good set of ear muffs only gets you about 20dB of protection.  
Now, in the referenced article, Dr. Branch measures the unsupressed and suppressed sound levels of several popular firearms/calibers at both mil standard distance 1 meter to left of muzzle and at the shooters ear.

Firearms:
1.Sig P226 (9mm) – Remington UMC 147gr ball – Suppressor: Advanced Armament Ti-Rant
2.Glock 21 (.45 ACP) – Remington UMC 230gr ball – Suppressor: HTG Cycle-2
3.Colt AR-15 16” bbl – M855 62gr – Suppressor: Gemtech G5
4.Remmington R700 – Remington 168gr BTHP – Suppressor: HTG M-30

Data (only including the data at the shooters ear):

9mm
Unsuppressed: 157.7dB
Suppressed:129.6dB
(28.1dB difference)

.45 ACP
Unsuppressed:162.5dB
Suppressed: 128.5 dB
(33.9dB difference)

.45ACP suppressed (wet): 121dB  (41.5dB difference)

5.56mm
Unsuppressed: 155dB
Suppressed: 134.2 dB
(20.8dB difference)

7.62x51mm
Unsuppressed: 157.2dB
Suppressed: 131.2dB
(26dB difference)

As you can see comparing with the chart above, the amount of sound suppression you get from the muzzle level suppression is far greater than the ear-level suppression and in all cases, got the sound level below the 140dB threshold. The same cannot be said for ear-worn protectors. Of course this is not to say that you should not use hearing protection with suppressed weapons because time-averaged cumulative noise exposure will also take a toll on the hearing. Overall, however, muzzle-level suppression will provide far better protection.  


[1] Wu CC, Young YH, Ten-year longitudinal study of the effect of impulse noise exposure from gunshot on inner ear function, Int J Audiol. 2009;48(9):655-60

[2] Berger EH, Franks JR, Lindgren F [1994] International Review of Field Studies of Hearing Protector Attenuation. Proceedings of the 5th International Symposium on the Effects of Noise on Hearing, Gothenburg, Sweden.


Edited for maths

Cool.

This thread is full of things I don't like.
1: Words
2: Numbers

I am angry at numbers. There are way to many of them.

Seriously great article. Doc, you should just tell everyone here to buy a suppressor

Will you give me prescription for one?

Jim

Now there's an interesting idea.

 

+eleventy billion, I need a prescription for three suppressors!



ETA and they need to be $4 at WalMart.





 

More Cliff Notes

Anything over 140dB = BAD

EarPro = not good enough (especially with fancy schmancy commercial plugs)

Suppressors = reduce sound levels below 140dB

Wet suppressor = really good

Shooting = fun

If only our legislators would pay attention to this study.  They care so much about the health of Americans that they pass legislation to mandate health care coverage for all os us, yet they allow legislation that is absolutely detrimental to the health of Americans to say on the books.  We need to repeal the suppressor portions of the National Firearms Act and make suppressors nothing more than firearms accessories which are sold over the counter.  For those worried about crimes committed using suppressors, acts such as poaching or murder would still be crimes, regardless of how quietly they were committed.  There is ZERO reason to endanger the health of Americans just because you are worried criminals might be quieter.

All I think the politicos would get from it is that they need to ban guns because they damage hearing.

Amen to those sentiments. I think data like this helps to make the case that suppressors aren't "tools of assassination." With millions suffering from hearing loss and decent hearing aids costing upwards of $3000 per pair, the burden of hearing loss on our system is not insignificant.  

And just to be clear, 130dB is not exactly "quiet"

Any way we can get this report reprinted and sent to some of our conservative congress critters while the ATF is taking heat?

 

You can download a PDF of the full article from the site linked above for $32 (hence the summary rather than just linking it).

I always wear ear muffs AND plugs.  The problem is I can't really hear anything with both on.  

Electronic muffs that amplify sound and plugs work great together.

 

5.56mm
Unsuppressed: 155dB
Suppressed: 134.2 dB
(29.8dB difference

Bad math

Strange, my. 223 can is quieter than my 9mm

Posted Via AR15.Com Mobile

I've heard electronic muffs don't block the loud sounds completely... there is a small time period before the electronics react and turn the mic off



 

That's what the plugs are for.

 

Yup... Good catch. The numbers were taken straight from the article. Fixed above.

First they make me put mufflers on my Harley ... now they want me to put a muffler on my pistol???

Exactly what I was thinking.

Both were actually invented at the same time, by the same person, for the same reason.  Unfortunately, one got mandated for use while the other was all but prohibited from use.  It's only been within the last 10 years that suppressor use has become almost common place.  We have the internet to thank for that, for the most part, as well as great leaps in suppressor technology and the fact that the $200 tax isn't as burdensome as it was in the past.

Electronic muffs are electronically filtered to reduce the dynamic sound range transmitted through the mic. It is impossible for them to amplify gunshot sounds, and for gunshots, they work like plain old muffs according to their published NRR. Unfortunately, as mentioned above, the amount of real noise reduction you get is way below the published NRR, and even if you add ear plugs into the mix, you are still at risk for hearing loss with long term use.

WHAT?

Doesn't the actual sound energy double for every 3dB

Yes.

<––––––––-Just bought a suppressor!

- Clint

hearing protection is a "good reason" for sound mods in the UK , they are cheap and have no silly stamp to pay .



just sayin

Doesn't the Finnish government actually encourage their citizens to get suppressors?

It works for the beavis/butthead quote and the fact that I would love to begin my tax stamp collection.

Well, um, my chainsaw is 115dB and it's louder than my Remmy 870 12 gauge w/ muffs.

The police officers' hearing may show decline because of 125dB sirens, unprotected gunfire, and other recreational activities.

The Military must think earpro is sufficient.....

There's a lot of when it comes to noise information, just look at OSHA and CDC noise charts. They don't match.

OSHA chart.
8...........................|                    90
6...........................|                    92
4...........................|                    95
3...........................|                    97
2...........................|                   100
1 1/2 ......................|                   102
1...........................|                   105
1/2 ........................|                   110
1/4  or less................|                   115


NIOSH(CDC) chart
16 hours 82
8 hours 85
4 hours 88
2 hours 91
1 hour 94
30 min 97
15 min 100
7.5 min 103
3.75 min 106

OSHA noise page

OSHA has more "experience" when it comes to things like this, so I follow their chart.

Still, why are they different?

The CDC chart is generally considered more accurate, mostly because it's newer, and the science has evolved a good bit over the years.  Do keep in mind that the organizations have different objectives for their data.  

I do question the "real-world" number for plugs presented in the OP... Only 5 dB?  I do most of my shooting with plugs only, and I have a really hard time believing that it's only 5 dB of protection

Most of those numbers are BS, just like made up numbers for suppressors. Each person is different and the chart doesn't take into account improper fitting and use.



If the ear plugs only decreased noise 5db, then my flying jets combined with shooting every weekend, I would be deaf by now.



Still cans should not be taxed

Wife is an audiologist, I'll forward this to her. Thanks, doc.

I'd like to see someone get a bunch of ENTs and audiologists together and challenge a state's suppressor ban.

Actually, the military has been buying suppressors by the boatload over the last several years.  Much of that has to do with the tactical advantages afforded the users, but the reduction in hearing damage is a consideration.

No question the hollywood depictions are as much to blame as anything.  People think being hit with a handgun will throw them through a window because that's what they see in the movies.  Likewise suppressors are likened to "silencers" capable of making a gun completely noiseless.  

The logic behind the current law is deeply flawed: a relatively expensive tax stamp creates a high barrier to ownership that neither makes them less available to criminals nor makes effective hearing protection easily available.

NIOSH and OSHA exposure levels vary on a lot of things.  NIOSH levels are the recommended exposure limit, OSHA levels are the  Permissible exposure limit.  You want to stay below the NIOSH (or even ACGIH) levels, but you are required by law to keep employee exposure below the OSHA limits.



There are a number of reasons for the difference.  Hell, some of the OSHA limits are well above what most consider to be the "safe" limit, but industry and lobbyists keep them from changing them to levels that would 'put us out of business'.



Another thing to keep in mind is that the charts you listed above are for exposure to steady state noise over a period of time.  OSHA also limits exposure to impulse (peak) noise levels above 140 dBA.



Still, I get (and agree with) your point that gunfire is not the only cause of occupational noise exposure, and that all of the high level noise exposure is cumulative.  However, the high intensity, relatively high pitch gunfire is definitely a major contributing factor to occupational related hearing loss.



 

We will become the medical marijuana of the fight for the RTKBA

It is just plain silly the way suppressors and suppressor technology is treated by the .gov. I try to explain the legal issues to non-shooting friends and they think I am just making it all up.

As one *mildly gun-control approving co-worker put it; "So, if you go to a gunshop and buy a deadly weapon and a silencer for it, you can walk out with the handgun and ammunition the same day but you have to fill out more paperwork, be finger-printed, pay a $200 tax and wait four months so the Government can decide if you can be trusted to use the silencer with it That is NUTS !!!

*  I say "mildly" because this guy grew up in a house without guns and just assumes gun ownership=criminal. I am slowly showing him the error of his beliefs and it is working.

I bet just the lifetime costs for a vet given partial disability for hearing loss makes suppressors a very attractive investment just on that end.



 

It would also help mitigate one of the biggest issues between ranges (private, clubs and public) and noise sensitive neighbors. Not eliminate the issue but it would help.

Me too. Picked it up a week ago. No plugs and no Muffs, fuck yea!!

Fascinating. I'll have to swing by the library to check for an institutional subscription.

I have always consider the medical angle the best chance of getting cans less/unregulated. Even more so when someone lives in a county/city where the CLEO won't sign-off.

So, based upon this, every shooter who doesn't have a suppressor will be deaf before too long