From what I can find, most all foam ear plugs have a NRR between 20-30db.  Earmuffs have less than foam plugs on average.  I have a 5.56 suppressor with a NRR of 34db......but yet, I'm told to wear ear pro while shooting a can; which I do!
The big question is....is shooting an unsuppressed firearm ear safe at all?  The conclusion I'm drawing is, shooting with foam earplugs inserted can still damage hearing.
Maybe this has been brought up....if so, forgive me!

If I'm at an indoor range, especially when others are shooting, I have foam plugs in and muffs on.

You only get one set of ears, and hearing loss doesn't come back.

You can shoot subsonic ammo with a can without using ear protection. The problem is supersonic ammo, which generates its own sonic boom in excess of 150dB. Additionally the ejection port noise on an AE exceeds 140dB and is right next to your ear. That is why it is recommended to wear ear pro with a silencer, as there is no such thing as a "hearing-safe" can when shooting supersonic center fire cartridges.

Regarding your question, yes, it is wise to not rely on a single method of ear pro when shooting unsuppressed. Most over-the-ear muffs which are popular have horrible NSR. Molded ear plugs are equally bad. Expanding foam plugs are best at 33-35dB NSR. If you are shooting a 9mm pistol held away from your face, one set is probably sufficient. If you are shooting a 10" SBR with a muzzle brake you should wear plugs and muffs.

I believe 86db or so is where damage to the ear begins to happen, so you might need to shoot inside an enclosure with your defense ammo and a measuring device to find out. Also, you need to take in mind the potential target; will they have a weapon? If so, then your can will not protect you from the sound of their gun. Also, does your ear pro take a long time to put in, and does it reduce your situation awareness? One might conclude that if you have a combination of earpro and a can that you are potentially reducing the sound suppression of your target whereas if you have earpro and an un-suppressed gun you would maximize self-preservation and effects on target. In order to reduce donning times and increase situation awarness, electronic earpro such peltors or similar combined with an un-suppressed weapon could potentialy maximize your survivability.
 

This is only true of constant noise.  Repetitive and momentary sounds do not have the same levels and everybody is different.  Shooting in enclosures, or with reflective surfaces will also change things.  There is also the concept of the supersonic crack and WHERE the supersonic crack is.  If you're shooting a rifle with a can, you're talking about the muzzle being over two feet in front of your face and if the supersonic crack has nothing to reflect off of, the volume at the ear can be hearing safe.

In general, I wear hearing pro with rifle and supersonic pistol.

ETA: This is where everybody is getting the "86db" and "140db" limits.  It specifically says, "Exposure to impulsive or impact
noise should not exceed 140 dB peak sound pressure level."

OSHA Noise Exposure Limits

140 seems a little loud, but you can't really argue with OSHA. Excellent response. I always like to read about hearing loss and what not since I'm somewhat deaf nowadays. I personally always recommend protecting your hearing, tenitis and not being able to hold a conversation is a mind fuck.

 

One microsecond of exposure at 140 dB =/= One second of exposure at 140 dB. A gunshot's peak sound level lasts for a small fraction of a second, and that's why OSHA guidelines are different for gunshots than for ordinary noises.

I worked the Flight Line for 24 years. Over the last 8 years, I dealt with OSHA standards to the point of nausea.  The limits are based on an 8 hour day, 40-hour week.  It caters towards factory and industrial workers, not casual tool use and occasional exposures.  I have good hearing because I was often overcautious.  I even wear ear pro when mowing the lawn, but not when shooting with 22 or pistol cans with subsonic ammo.

I would be comfortable just wearing foams or overs with a suppressor.

I always double up for most shooting. I find I can hear/converse find with the foams in. Doubling makes a big difference in comfort over long strings.

Don't listen to the morons who say hearing damage doesn't start til 140db. Everything you can do to reduce the noise will help you preserve your hearing, including shooting outside, using a can, and doubling up the ear pro.

WHAT?!

 

While I think this advice is excessive, the premise is correct: OSHA lists the 140 dB number as the maximum impulse noise an average person can be exposed to ***one time***  without suffering permanent hearing damage. If we increase the number of exposures, the maximum dB number goes down.

Plus, all human ears are different, and the OSHA figure isn't any good for outliers who have especially sensitive ears. Most things in health and the human body are bell curves, and I'm sure that hammers/anvils/stirrups/auditory nerves are no different.

Disagree. It is unfortunate that everyone quotes OSHA Regulations as factual when it comes to a medical question. Damage to the hair cells of the inner ear will begin with impulsive noise well below 140 dB. While that may be enough to satisfy an OSHA inspector at a large factory, it should not be what prompts you to expose your own ears to such sound. The best centerfire rifle silencers meter in the mid 130s which, for the purposes of a medical hearing discussion, is almost identical to 140 dB. At the ear they still meter well over 120dB on bolt guns, and typically 142-144 dB at the right ear on an AR-15 due to ejection port noise.. Hearing damage occurs on a spectrum, and impulsive noise does not magically become safe below 140 dB. 135 dB will damage your hearing virtually as quickly as 140 dB. 125dB is an improvement but should not be regarded as safe for repeat exposure. Those who value their hearing will wear ear protection with all supersonic suppressor use. The ear surgeons I work with are in full agreement with this.

Why are you reinventing the wheel? The EPA, OSHA, NIOSH, and ANSI all have published standards for the testing of hearing protection. That's how the NRR gets published on every ear pro device, and plugs are rated best.

Agree with this. The problem is that, by using OSHA regulations as a substitute for physiologic expertise, silencer manufacturers have convinced their customers that sub-140dB is a "dose" at which no amount of "time" will constitute an unsafe exposure.

I'm sorry, but your 'experience' working with ear surgeons does not one-up me any more than my experience running an OSHA hearing conservation program for 8 years trumps you.  I quote OSHA and you say, "well, I know better and OSHA is wrong." Okay, quote another source.  Working with rivet guns is VERY similar to gunfire. We had all the fancy testing equipment and annual hearing tests for years or decades in my case.  We also wore hearing protection nearly constantly as I have suggested you do with supersonic rounds.  My point, that you disagree with apparently, is that if you are shooting rifle with a can, it can be hearing safe in some situations.  Is there a COSHA (Conqueror OSHA) regulation that lists different standards?

The point of a suppressor is to protect your hearing. Why would you buy a suppressor and then take off your hearing protection? Is 20 ounces and 6 inches added to your rifle worth getting rid of your ear plugs? Use both, save your hearing.

While I certainly don't disagree with your statement in general terms, not everything you do to reduce the noise will in fact, reduce the noise.  With ideally made and inserted plugs and with ideally made and worn muffs, you probably aren't going to see noise reduction much beyond 40db, with some freqs having a lower limit, if I understand the science correctly.  Certainly, if wearing plugs and muffs helps, it can't hurt.  But don't believe that if you add -30db together with -25db, you are going to get anywhere near -55db in reduction.



In my opinion, this is one of the strongest arguments in favor of suppressors.  



With center fire, semi-auto arms, I'd wear at least plugs or muffs at the range.  Hunting I may be more inclined to rely on the suppressor alone or in addition to a right plug only.



 

this

In a HD situation I would prefer my can, but I am wearing ear protection every other time I shoot.

10.5" SBR, 6" can.  Go all the way.

I'm sorry too, but yes, it does. I am a neurosurgeon and team up with otolaryngologists and neurotologists to treat ear diseases (among other problems). OSHA is not a medical organization, and has no medical expertise. If OSHA defined a heart attack a certain way and Cardiologists disagreed, which group would you trust? The OSHA regulations are not designed to be a best-practices guideline for biologically-safe exposures. They are designed to create an employee-weighted middle ground between the need to protect employees and the realistic need of industrial employers to expose employees to unsafe noise. Your experience as an OSHA regulator unquestionably means you are an expert in what the government has defined as "acceptable noise exposure." But what the government has defined as acceptable and what expert physicians define as ideal are often at odds. The government also defines acceptable amounts of rodent feces in food, but that doesn't mean rodent feces are safe to eat, nor would most people like their food to be right up against the regulated quantity of feces.

Here is a good, brief read: http://www.audiologyonline.com/ask-the-experts/niosh-and-osha-permissible-noise-247

In short, OSHA has the loosest noise regulations and many workers can be expected to experience hearing loss even in OSHA-compliant settings.

The CDC acknowledges that 140dB is largely arbitrary: http://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf

"The generally accepted ceiling limit of 140dB peak SPL is based on a report by Kryter et al (1966). Ward (1986) indicated that 'this number was little more than a guess when it was first proposed.'"


Yes, we still disagree on that if the rifle is a centerfire rifle with supersonic cartridges, as I said above. You can fire all the subsonic .308 you want, pretty much. But with supersonic ammo, even very good rifle silencers meter unacceptably loud at the ear, with maximum permissible exposure sums well under one second, even when used in favorable conditions like on a bolt-action rifle. On a semi-automatic rifle the entire argument is moot because the ejection port fires 145dB noise directly into your right ear, which is unsafe even by OSHA's loose standards. I'm not sure why you had to stoop to sarcasm and ad hominems to make your point but they are unwelcome if you want to continue this discussion.

My ears ring slightly if I fire a 5.56mm carbine with a suppressor, and no ear pro, even out in the open. Regardless of what meters and OSHA say, that tells me that it's not hearing safe.

It's still a LOT better than unsuppressed, of course, if I have to fire it without hearing protection.

FYI ears ringing is not a great test for hearing safety. If something makes your ears ring there's a decent chance it is unsafe, but the converse is not true in the slightest (ie, lack of ears ringing does not imply safety). Whether you experience post-exposure tinnitus is heavily dependent on the prior condition of your hearing and highly subjective.

the last time i shot my rem 700 .308 with the can, i shot about 40 rounds, no ear pro.  no ringing, no pain, nothing.  

however, not the same with my AR.  it doesnt hurt my left ear, but it does my right.  right handed, probably the action cycling that lets out some noise.

Didn't say you could add the numbers together. But the simple fact is that the more layers of protection and prevention you have there, the better off your ears will be.

I'm sorry, I thought I was being lectured.  A discussion would be where you say something to the effect of a counterpoint.  For instance, you COULD have said, "Yes, Badger Arms, you are correct that under some circumstances, shooting a suppressed centerfire rifle can be hearing safe.  But, I would caution that you are better to be safe than sorry."

The Layman will call BS on all of this and shoot the gun without ears anyhow.  If his ears don't hurt or ring, he'll keep doing it.

yep, my ears my rules

some of you have never been to a rock show it seems...

I wear plugs at concerts. I'm not nearly cool enough to be deaf.

That's not what you said earlier. You specifically mentioned sonic crack, so you were talking about supersonic rounds. Therefore "you are correct" could not be said. If you would like to expand your point to include subsonic cartridges, then yes, I will concede that some (not all) are hearing-safe.

It's like arguing with a wall.

I know that I learned enough in physiology and neuro to make sure I damn well protect my ears. The little dental handpieces aren't nearly as loud as a gunshot and they cause hearing loss anyways.

I never said otherwise. I merely said that I needn't resort to any other (or more precise) testing to know that a suppressed 5.56mm carbine isn't hearing safe, because it makes my ears ring and thus I know it's not.

I'm just going to put fruit gushers in my ears and tie a pillow to my barrel and call it a day.

Ah, discussion again.  The supersonic crack is not an omni-directional sound.  It is directional at a 90-degree angle to the shooter.  The 'direct' sound heard by the shooter from a supersonic crack is, generally speaking, hearing safe.  But, if there are any hard surfaces nearby to reflect that sound, it can be very loud.  The further the end of the suppressor from the ear of the shooter, the less likely this reflected and refracted sound will be intensive enough to cause long-term hearing damage.

there was another thread about the sonic crack a few weeks ago. supposedly it doesn't occur at the muzzle but a few feet in front, I don't remember the exact amount but iirc it was ~20'

Even though plugs have a good NRR rating, most agencies realize that the labratory readings, don't match real world fit, and give de-rating guidelines.

NIOSH, Criteria for a Recommended Standard, Occupational Noise Exposure, June 1999
•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

When you take into account the de-rating, most muffs beat out plugs, but in true ARFCOM fashion if your shooting indoors, or a large amount of big rifle get both.

Didn't you hear the rocket surgeon?????  He told you how it was...now go away....

The OP specifically states he is suppressing 5.56.  If it hasn't been pointed out thoroughly yet, I will highlight the fact that there are gas ports on the side of the bolt that 'pop' when the bolt operates.  That pop alone is not hearing safe.  No AR-15 or AK-47 with conventional gas systems should be considered hearing safe.


As the apparent wall in your analogy, I will point out the irony that walls in general reflect sound and therefore, arguing with a wall might result in reflected sound and be pretty loud.


On a conventional, unsuppressed rifle with no muzzle device, there is a jet of high-speed gas that comes out of the muzzle prior to the bullet.  This gas is not going fast enough to 'buffer' any more than a few inches at most in front of the muzzle, and maybe even less than that.  It is pretty much right as it leaves the muzzle, therefore.  It occurs to me that there is a general ignorance of supersonic crack.  I'll post an image below.  That little 'V" shaped wave you see at the front of the bullet is directional.  It ONLY goes sideways.  In the absence of any obstacle, somebody alongside the path of a supersonic bullet will not hear the entirety of the supersonic crack from the entire path of the bullet and the same is true of the shooter.  The observer will hear the sound coming from a 90 degree angle to the path of the bullet EVERY TIME.  The suppressor only stops the baloon-shaped muzzle report.  Note the curved, omni-directional nature of the waves coming from the muzzle.  Now, on a suppressed rifle, the bullet comes out with very little in front of it and the supersonic crack will therefore look pretty clean.

Neurosurgeon?  In my experience, medical doctors do not spend a whole lot of time sparring with internet commandos so I'm waiting him out.

interesting, I was never convinced entirely by the poster making that claim but it seemed worth mentioning

is that photo real or some kind of artist's depiction?

Whether or not the supersonic crack is hearing-safe in isolation is irrelevant to this discussion. A good rifle can will measure 130dB at the shooter's ear. No one has studied whether that 130dB noise is 90% residual muzzle blast and 10% sonic crack or the other way around. But if the resulting combination, whatever the source, is 125 or 130dB, the composition of the blast is irrelevant because it's unsafe either way. The statement "there is no hearing-safe supersonic centre fire rifle silencer" still stands.

The apparent lack of a sonic crack for bullets that travel a few feet before impact is most likely from the very short duration of the crack.
Not enough time for your ear/brain to register it as a sound.

makes sense

found a thread on a physics forum that has more information on the phenomenon science

if I'm reading it right, it seems that the further the object travels, the more waves are generated - they then coalesce into one perceived "crack"

so less travel distance, less total waves generated, shorter crack duration

There are actually two sounds in a sonic 'crack'. The first is generated from the front and the second from the rear of a bullet.  The second one travels slower than the first.  I lived on the descent path of the Space Shuttle and had the luxury of watching live broadcasts that would tell you the speed of the shuttle as it descended.  My math is fuzzy, but I believe it was at about 200,000 feet over the top of my house and going Mach 4 or thereabouts.  The two 'booms' were about a quarter second apart.

Translate that to bullets and I don't think a human can perceive the two cracks as distinct at any reasonable distance.

I have only been exposed to a couple suppressors and hosts but a bolt action 308 with a can surprised the hell out of me. I've heard a 300blk which I was expecting to be quiet and I have heard suppressed AR's which i expected to be a bit noisy. But a full power 308 is plenty quieter than an AR, way more pleasant to shoot with no ear pro.

1988 I saw Ted Nugent at Hammerjacks in Baltimore.  Didn't wear earplugs because I was a stupid college kid.  Ears rang for three fucking days after.  Hearing was tested years after that and I came out normal, but that's not to say that my hearing might have been slightly damaged.

I think I would have to agree with the supersonic crack thing next to or in front of a muzzle. Had a .50 rocking one time to cover movement and it was painful on the ears until I made it behind the gun, then it was just loud.

I am an ENT and can speak to this.

Conqueror is correct.  The OSHA standards are arbitrary/flawed and in need of updating.  
Shooting a suppressed aR15 without ear protection of any significant round count is a bad gamble.
I always recommend plugs or muffs because of the ejection port noise, it's just too loud.

The easiest way to put this is if the sound makes your ears ring then your hearing is at risk and at that point it's potentially too late.
Ringing/tinnitus can be temporary or permanent and is usually associated with some measurable change in hearing(called a threshold shift).
This goes for hearing loss as well.
I have tinnitus and have the benefit of years of audiograms showing a slow progression of hearing loss.  
The tinnitus showed up first and then a corresponding hearing loss a few years after in the same frequencies as my tinnitus.


I have done testing of custom fitted plugs compared to ProEars Gold muffs(best on the market) and they are essentially equal at about 30dB NRR.
Custom made plugs are cheaper and more comfortable but you don't get the amplification of the muffs.
I personally wear both when I'm shooting high volume, suppressed or not.  This drops an additional 5dB(logarithmic scale) which is double the actual power reduction of either alone.

There was a medical article in a major ENT journal a little while back that did independent testing of commercial ear protection and most failed miserably.
When in doubt just use foam ear plugs but if you want muffs alone without plugs I won't wear anything except ProEars Gold.(I don't work for the company and bought my own)

One other thing to mention: the other benefit is that a suppressor does reduce the amount of sound reaching the skull which is also transmitted through the bone to the inner ear.
To me this is significant especially with SBR'd AR's and in larger calibers such as 300WM, 338 Lapua and 50BMG.

When subject matter experts who have spent their adult lives acquiring knowledge like Conqueror, myself and Dr. Dater say something we're not trying to pick a fight.
We want you to hear your grandchildren.

This.

Exactly, but you can go with foam and a can if you're at an outdoor range.

I would only use a can an no earpro for my 22 or in a SHTF situation. YMMV, depends on how far into your old age you want to be able to use your ears.

And if anybody does what I just did and Google "Pro Ears Gold" and sees them on Amazon Prime for $290 and think "uggh", go ask anybody that's lost their hearing if they'd be willing to spend ~$300 and get it back. It's a no-brainer.

I'd never heard of them, and will readily admit I look at NRR and price when grabbing new muffs, and tend to pick up the cheaper ones. I didn't like the way my heavier duty NRR30 muffs hit the stock, so I bought some Howard Leight low profile muffs that only have a 23NRR, but always combine it with foam plugs in the 29-32NRR range. This is especially true indoors with lots of other shooters.

Also...do others a favor and keep spare foams and even a set of muffs in your bag. You never know what someone will bring if you invite them to the range, or what somebody may forget.

But I also wear foam plugs when mowing the yard, blowing off the driveway, or cutting down a tree...no matter how quick it may be.