inside gunfire effect on hearing

[MikeNice]

Klean, a 3db increase means the amount of energy that goes in to making the sound was doubled. To actually make something sound twice as loud takes 10db.

I might be wrong on the 10db part, but I know I am right on the 3db bit.

 

[benEzra]

So, in terms of sound pressure, as I try to (struggle to) recall what I studied in a physics class shortly after the 1964 model cars had come out, ...

* The 9MM is about twice as loud as the .38 Spl.
* The .357 Magnum is about twice as loud as the 9MM
* the .45 ACP is a little over half as loud as the .9MM

Well, our hearing is logarithmic too (not linear), so twice the sound pressure isn't perceived as twice as loud. As a rule of thumb, a 10dbA change equals a doubling in perceived loudness (even though it represents a tenfold increase in power), and a 1 dBA change is barely noticeable by the human ear, so a 2-3 dBA difference would be noticeable but not huge.

There is some interesting discussion downthread here:

http://www.newton.dep.anl.gov/askasci/eng99/eng99325.htm

Those dB charts must not take into effect the frequency of the noise or something because according to that, a 9mm is substantially louder than a 5.56, and my own unscientific test of shooting without ears on was quite the opposite.

I believe those are dBA figures, which do take frequency into account, but they are *peak* dBA, not total radiated power integrated over time. It is possible that .223 has a longer off-peak duration, for example. Also, the lower frequences do less damage to hearing and are weighted less heavily on the dBA scale than higher frequencies, so it is possible that a .223 could be deepier and "boomier" than a 9mm without having a higher intensity in dBA.

http://www.eie.fceia.unr.edu.ar/~acustica/comite/soundlev.htm

Also, there is a tight correlation with barrel length, and that .223 figure is for an 18" barrel. A 16" .223 will be somewhat louder (probably comparable to 9mm), and a 14.5" .223 will be more like a .357, I suspect.

dBA does correlate pretty well with hearing damage.

 

[Kleanbore]

Posted by MikeNice: Klean, a 3db increase means the amount of energy that goes in to making the sound was doubled. To actually make something sound twice as loud takes 10db.

You are correct. That's why they call them "decibels".

I was imprecise in my comments above, in that I improperly described the ratio of sound pressure as "loudness"." I didn't want to appear too scientific.

However, I think it is the the pressure increase that is relevant to the discussion of physical damage. I think we are not concerned with the subject of how loud someone senses one sound to be vs. another, but with the pressure that impacts the sensory system.

Of course, frequency and duration will figure in, in addition to amplitude.

It would seem to me that firing indoors increases the duration of the sound over what happens outside, when the wave propogates away from the sound source without being reflected back and reflected yet again until the energy dissipates.

Your thoughts?

Posted by benEzra: Well, our hearing is logarithmic too (not linear), so twice the sound pressure isn't perceived as twice as loud. As a rule of thumb, a 10dbA change equals a doubling in perceived loudness (even though it represents a tenfold increase in power), and a 1 dBA change is barely noticeable by the human ear, so a 2-3 dBA difference would be noticeable but not huge.

Very true indeed.

So, the question is, regardless of what we "hear", what is it that does damage, and how much of it matters?

I haven't worked with any analysis or testing of the physics of sound for about forty five ears, and I haven't done any in depth work with logarithms for about fifteen, so I am not the guy to figure these things out. However, going back to the link to the study above,

Krammer adds that sound pressure levels for the various pistols and ammunition tested yielded an average mean of 157.5 dB, which is greater than those previously shown for shotgun and rifle noise levels. There was also a greater range, from 152.4dB [.32 Long] to 164.5dB [.357 Magnum], representing 12 dB difference, or more than 10 time as much acoustic energy for the top end of the pistol spectrum.

Krammer refers to the tenfold increase in energy, rather than to a doubling in loudness.

My takeaway from that is that there is a substantial difference among handguns in terms of their potential to cause permanent noise-induced hearing loss, and that the .357 Magnum, particularly with a short(er) barrel, is among the worst.

 

[Erik M]

I was in the room about 5 feet away from a ND out of a Glock 30. My right ear rang and ached for 4 days and I went to my doctor because I was scared it would be permanant. The fact that we were in a closed room with no windows seemed to make it worse in my mind.

 

[merlinfire]

I shot a shotgun (bolt action 20ga mossberg) for the first time with no hearing protection, I had a headache for 3 days. Learned my lesson. And that was outside, at that

 

[o Unforgiven o]

Im confused now... That link that Harley Quinn gave said this;

Based on the logarithmic scale, a 3-dB increase in SPL represents a doubling of the sound intensity.

But according to you guys that is not true.

Either way I always wear hearing protection in the form of Surefire EP4's, and if shooting centerfire rifles or handguns I wear the EP4's with Howard Leight L1's over them.

 

[benEzra]

So, the question is, regardless of what we "hear", what is it that does damage, and how much of it matters?

Hearing damage pretty much tracks with the pressure and/or power of the sound, which is what is tracked by the dBA (log10) number. Damage is not correlated very well with perceived loudness. Damage is strongly frequency dependent, though, which is why the A-weighted scale is used, to reflect the ear's frequency response.

Based on the logarithmic scale, a 3-dB increase in SPL represents a doubling of the sound intensity.

But according to you guys that is not true.

It's a little easier to see in a graph than to explain in words:

http://www.animations.physics.unsw.edu.au/jw/dB.htm

Mathmatically speaking, a decibel measurement is always a ratio between two numbers (say, the power of sound #2 vs. the power of sound #1) and is expressed as the logarithm of the ratio between the two measurements:

dB difference = 10 * log10 (s2/s1)

so if sound #2 carries twice as much power in watts per square meter as sound #1, then the difference between the two sounds is just over 3 dB:

dB difference = 10 * log10 (2/1)
= 10 * 0.3010299957
= 3.010299957 dB

If the ratio between the two sounds' energies is 10 to 1 instead of 2 to 1, it would be 10 dB:

dB difference = 10 * log10 (10/1)
= 10 * 1
= 10 dB

When used as a sound-level scale, the denominator of the ratio s2/s1 is the pressure or energy of the faintest sound that a human with perfect hearing can detect in a perfectly silent room. So a .357 magnum at 164.3 dB is 10^16.43, or 26.9 quadrillion, times as intense as the faintest sound someone with undamaged ears can hear.

The perceived *loudness*, though, doesn't increase as fast as the energy/pressure; for every tenfold increase in power, perceived loudness only doubles.

 

[Zoogster]

It would seem to me that firing indoors increases the duration of the sound over what happens outside, when the wave propogates away from the sound source without being reflected back and reflected yet again until the energy dissipates.

Absolutely.
Every shot indoors is experienced at near peak intensity for a much longer duration than the same shot outdoors.
This makes hearing damage far more likely.

The sound waves will reflect back and forth from hard surfaces and continue to hammer the ears until they run out of steam. While outside they continue to travel away from the location of the shooter. The ground is the closest hard surface outdoors, but even then the intensity is diminished as the angle the waves impact the ground send most of them away from the shooter.
In a rural outdoor environment with soft soil, living tree bark, bushes, grasses or ground cover, and other soft objects the sound will be more absorbed so what does eventually reflect back has been severely diminished in intensity.
Even further reducing the overall loudness.


Indoors the walls and ceiling are often hard flat surfaces that will direct the sound right at the shooter. The floor may be carpeted, but the space is still enclosed (further increasing the effects of the pressure wave.)
The sound waves will ricochet endlessly in an enclosed space until they run out of steam.
The smaller the space the worse the effects. A bedroom would be bad. A kitchen or bathroom with all hard surfaces would probably be the worst as the sound would reflect from those surfaces with the strongest intensity.



This means a shot fired indoors without hearing protection from many calibers will be worse than several shots outdoors.

Hearing damage is cumulative though. So as a person becomes more deaf or loses hearing of various frequency ranges they are less sensitive to the pain and damage of a similar decibel loud noise.
Allowing them to further damage their hearing with less discomfort.
People partially deaf don't notice what they can't hear until it typically has progressed pretty far.
The subtle rustling of the leaves, distant chirping of birds, a small animal moving in the brush, a gentle lapping of water, the majority of such things will just be absent from their perception.
It is not until the much louder noises like a person talking in a normal tone become difficult to hear that they typically realize they have a problem.
By then they have lost a lot more than they had realized.

 

[benEzra]

Absolutely.
Every shot indoors is experienced at near peak intensity for a much longer duration than the same shot outdoors.
This makes hearing damage far more likely.

Yep. And consider that those decibel measurements upthread---all of which are way above the dBA threshold for permanent hearing damage---are very likely the quieter, outside measurements.

FWIW, there are a couple of Schlieren pics of the sound waves from a revolver and a short-barreled AK here.

 

[pfraser]

Having been in a room where someone lit off a full-song .44 Magnum, I can tell you that firing indoors sucks.

Having said that, self defence situation? I don't care if I'm deaf, I'm still alive.

 

[therewolf]

I was at the indoor range one fine day, shooting my 1911.

Normally using ear protectors, I didn't give it a second thought,
until the rangemaster came up and spoke to me for a couple seconds.

I went back to my shooting afterwards, forgetting to put the ear protector back on my right ear. I was surprised to say the least at how loud the shot was.

And that was only standard 230 grain .45 ACP...

 

[dadof6]

I was not contemplating the use of hearing protection in the event of a BG coming into my house at 2 am. For many reasons, that just wont work.

I was thinking actually about being distracted by knowing what is coming if I press that trigger all the way. I shoot out of doors, but under a covered roof. I fired a .45 once, and my ar-15 once. the 45 really hurt. the AR? well, I only took one muff off. I was so startled and in pain that i scrambled to put the muff back on, as if I thought it would make it feel better The muzzle break really makes that thing xtra loud.

I have always used muffs, both for shooting and when i work in my basement shop. And yet I am loosing my sensitivity to sound in the range of the human voice.

I was just wondering if anyone had faced a situation where they fired indoors against a threat, and if knowing they had no hearing protection hampered their concentration. And/or, did the blast do anything to the other guy (not counting lead poisoning) to scare or stun him and allow a victory.

thanks for all the excellent replies and data. I will need to read that over more carefully.

 

[FriedRice]

During training a month ago, I forgot to put on my muffs before a drill. I use the gill type ear plugs, then electronic muffs over them. I had one gill fairly well seated in my right ear and the left ear less well seated. 20-24 shots went off around me before I got my ear muffs on. I haven't been to the doc yet but I suffered immediate pain in the ear drum (no rupture) and tinnitus off and on since then. For the first few weeks it was left ear, the last week it's been the right ear. It only lasts 10 seconds or so but the pain is often much longer. My hearing doesn't seem to be diminished in an obvious fashion but if I lose my hearing, I lose my livelihood. I will not make that mistake again. I also do not intend to shoot indoors again until the pain is gone. In addition, I'm joining an outdoor range.

 

[Sunray]

"...the possible exception of a very few calibers..." None. One shot out of any .22 LR, inside, without hearing protection, will cause permanent hearing damage.
"...the gill type..." A gill is a unit of measure.

 

[Hardtarget]

Some years ago, I shot with a club that used a range that was "open air". There were walls and back stop. and a shed roof where the shooting line was...just no roof. So, I come in, close the door and look up as the targets "faced". I think six .45s went off together! I ran back outside and put on my muffs. My ears rang for three hours. I can only imagine what its going to be like shooting inside my house! I only hope that soft furniture and drapes help soften the the blast.

I've had my ears blasted four or five times in my life. Probably why they're ringing a bit right now.

Mark

 

[FriedRice]

They were shooter's ear plugs. They look like fish gills, that's why I called them that. I don't know how I have been able to hear without noticeable reduction since then. I'm usually in a quiet room talking 1:1. We will see how I do with ambient background noise this weekend. I'm sure I've done damage. That tinnitus is the sound of nerve endings dying. But it's not noticeable yet.

 

[twofifty]

great info here.

I am going to start a new thread on possible mitigation measures when designing & building firing line structures.

 

[Dulvarian]

I think that since silencers are legal here in SC, maybe I will just get one. That seems so much easier than worrying about the noise level.

 

[carbuncle]

I pesonally double up when shooting. I'm 29 years old, and already have a great deal of hearing loss (including near-constant tinnitus) because in my teenage years I thought I was invincible, and stood too close to the speakers at too many punk shows.

So it isn't just me! I have to double up, and wear plugs at any music show now. I'm 40, the cause of my hearing damage is exactly the same as yours, but with a decade of playing in bands added to it: next to impossible for me to make out a conversation among several people in a noisy environment now.

Back on the OP's topic, I once was shooting at an indoor range. The guy in the lane next to me was shooting a large-bore revolver of some sort, and when I turned my head for a second the edge of my earmuff lifted up at the same time the guy touched of a round: my right ear is still ringing from that, and it happened in '98. Seriously.

But from everything I've read, the bang will be the last thing you are worried about if you have to fire a gun indoors in defense...

 

[Old krow]

I think that since silencers are legal here in SC, maybe I will just get one. That seems so much easier than worrying about the noise level.

They're legal here and I'll pay the $200 tax stamp just to not have to worry about a logarithm again.

 

[coloradokevin]

I definitely think there is a serious risk of hearing loss by shooting indoors without hearing protection. How much hearing loss actually occurs probably depends on the individual, the weapon, how many shots were fired, and how close the shooter's ear was to the muzzle when the shot(s) were fired.

I imagine that part of the reason that this topic isn't discussed more often is simply because this ends up being a choice between the lessor of two evils: lose hearing, or lose your life. Personally, I think this subject makes a good argument for a suppressed weapon, though those aren't always easily available (especially thanks to the ridiculous $200 tax per item). I know that at least one sheriff's office in my state has suppressors on their AR-15s, which I think is an excellent idea. Unfortunately my department isn't quite so progressive, and we have regular 16" barrels with flash hiders... They're loud when they're close to your ear, even with hearing protection.

I actually carry a set of ear plugs in my uniform shirt pocket, just in case I ever end up in an environment where putting them in is advisable, practical, and necessary. In normal building clearances these plugs aren't used... I prefer to be able to hear everything during a slow/methodical clearance, and I calculate the odds of firing a shot to be relatively slim. However, I'm guessing that ear plugs might be useful (for example) when pursuing an active shooter through a building, especially given the proximity of my cover officers' muzzles to my ear during some of these tasks (but, such plans might go out the window during such a dynamic entry)! For home defense I just take the risk of hearing loss, and figure there isn't much I can do about it.

 

[FriedRice]

I realize people choose different calibers for defense but in that small dark room with me were two 40s, two 45s, and seven 9mms. Twenty plus shots at close range and I can still hear. I did not go deaf. My carry weapon does not permit a silencer however I do feel like I could probably withstand the hearing loss involved in a shooting with my 9mm. If I had an option for home defense, I might consider a silencer. I will take extra pains to protect my hearing but in a way, it was a good experience for me to have. I got muffs on ASAP and finished the drill. I got a pretty good experience of what would happen with my ears, and pushed through it.

I will report back after I see the audiologist though so others can learn. I'd already been developing tinnitus from 200 rounds/week of indoor shooting even with double protection. That was of about nine months duration.


Sent from my iPhone using Tapatalkze

 

[dadof6]

I was thinking that the blast, well aimed or not, might also startle the BG alot. I know when I'm pressing the trigger. it will come as a surprise to him (or her).

On occasion i have taken some kids (teens) to the range for some fun and safety lessons. one thing I have done is to have them stand away from me, out from under the canopy and take one muff off. I fire one shot.

then I ask them what they thought of that sound. then I talk to them about what they see on tv - fire fights inside warehouses and such. I want them to start to grasp the reality of firearms and break the hold that tv has on their imagination.

they are usually impressed with the reality lesson, and no harm has come to them (they stand a good ways off behind me). Puts a whole different spin on what 'cool' is.

Next im going to work on the realities of Halo on Xbox

 

[leadcounsel]

Use $60 electronic ear muffs. Put them on/near your home defense weapon. Noise at night, pic up your weapon and put on your muffs. Electronic ear muffs will amplify the soft noises and dampen the loud ones and benefit you.

 

[MrWesson]

I would rather be alive and deaf than dead.

I don't shoot without hearing protection but If I need to defend my home well what happens happens.