Question about electronic muffs.

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PinnedAndRecessed

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I'm looking at the Peltor tac muffs. They only reduce the noise by 25 dB. A 357 mag will generate 164 dB of noise. That's still 139 dB of noise to reach your ears.

That's still damaging.

Or am I missing something?
 
IIRC Decibels is an exponential (logarithmic? someone help me out) so like the Richter scale for an earthquake, each decibel is bigger than the next.

So in the completely grunt caveman terms I'm capable of explaining it, the "decibels at the end are lots bigger".

So when a noise reducing product only reduces say 20 of a 193 decibel sound, it's still way more than a 50% reduction etc.

Or I'm completely wrong... :D
 
Ok. That almost (to me) makes sense. I knew it was logarithmic on the sound end. I wasn't aware it was also logarithmic in terms of muffled noise.





Now I'm really confused.

:)
 
There's too many variables. Are you shooting indoors or outdoors? How much sound reflection are you getting off nearby surfaces (walls, roof, etc.). How many shots are you going to fire? Is the gun ported? On and on and on. The safe route is to double up and use both plugs and muffs.
 
I would normally agree about doubling up with muffs and plugs, and up until yesterday I thought that electronic muffs were a luxury. But with electronic canceling muffs, plugs would undo all the benefits.

Last Sunday I participated in my first USPSA match and there's a bit more in the way of range commands and info you need to hear than what you get during normal range time...

Like cell phones, broadband Internet, DVR's/TiVo that have come before, when it comes to electronic muffs, I "get it" now... :)
 
You might try the plugs and muffs yet--just jack the volume on the interior speakers of the muffs up loud enough that you can make it out despite the plugs.
 
I really have no way of knowing for sure, but my guess is if a fellow was trying to find out exactly how man dB a .357 or any other gun puts out, they'd check it in front of the muzzle. While it might be 164dB at the muzzle, it won't be 164dB back where your head is. I'm a musician by trade and I know that if I would put my ear right down in front of my guitar amplifier, I'd be deaf in a matter of minutes but should I stand behind my amp (similar proximity to a .357 that you're firing) the intensity drops WAY down...perhaps this has something to do with it...

Oh, and
So when a noise reducing product only reduces say 20 of a 193 decibel sound, it's still way more than a 50% reduction etc.
Click to expand...

is a huge factor!

I'm also a certified sound-tech (Peavey sound school) but sadly I've forgotten most of the math behind dB theory....it's been years ago. I do remember, however, that an increase of 6dB essentially makes the sound twice as loud...so if you go backwards 20dB, that's like 1/12th as loud? Never been good at math, but I think that's close!

Ben
 
I usede to use foam plugs or muffs as an either/or method. Then, I tried the plugs together with the muffs, and the gun shots were muffled to the point of near non-existance. The only problem was that usnig both also made it nearly impossible to hear range commands. The difference when using foam plugs together with electronic muffs is like night and day. I can hear range commands clearly, while all the reports of the gun blasts are almost non-existant. I'll only shoot any other way now if I have absolutely no other choice.
 
Silicone and muffs for me ...

The electronic muffs do look like a great idea (esp. as someone said for things like competitive shooting with lots of loudspeaker-borne announcements, but since I don't do any of those ...), but I like the few extra dbs worth of protection I get (at least on paper) from my Remington muffs (claimed 30 or 32 db reduction) compared to the low-end electronic ones I've looked at.

I usually wear these in combination with ridged silicone in-ear plugs.

However, I only wish the result was the near silence that some people are reporting! Even with plugs and muffs, I find the report to be rather loud -- loud enough that it's one reason I'm glad I can't afford to shoot more than 100 rounds on a typical outing. Perhaps I could have my ears modularized, and keep in them in the car while I shoot? Or perhaps I can find muffs that fit *over* my muffs ...

timothy
 
That's still damaging.
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You are correct sir!

According to NIOSH, MSHA and OSHA, hearing damage starts at 85 dB. Any noise above that level can cause a temporary (or permanent) threshold shift in your hearing. (DAMAGE.)

A 3 dB rise in noise intensity is Double the noise. (88 dB is twice as loud as 85 dB. and 91 is twice as loud as 88.) 164 dB is a substantial amount of hazardous noise.

Small arms fire, that sharp crack, is "impact noise" which is believed to more hazardous to your auditory system than "mixed noise".

Doubling up your hearing protection by wearing foam ear plugs under your ear muffs helps, but less than you may think. IIRC, NIOSH allowed 5 to be added to the higher NRR (Noise Reduction Rating) of the two types of protection to be worn. So, if your foam plugs had a NRR of 31 and your earmuffs had a NRR of 25, you could add 5 to 31 and have 36 dB of NRR.

164 dB - 36 dB = still too much noise intensity......

Seems to me that we should all get "canned" .........pardon the punnnn.

NailGun
 
While combining plugs and muffs alone may not provide enough protection to reduce exposure below 85 dB the short duration of the impulse noise reduces the exposure time such that managing noise exposure with a combination of protective devices and limiting time on the range can be accomplished.

Using electronic muffs with quality plugs properly inserted will allow you to turn up the muffs to hear range commands while the circuits shut off the speakers during gunfire.

The US Army considers noise from small arms fire to be ~157 dB. Various other sources have ranges of data on different weapons. In other discussions on hearing protection and small arms noise here in General there are tables from the Army's noise exposure controls document.

Impact noise, like that from gunfire, is fundamentally different from constant noise, but the damage it does is based on the SPL and the time exposed to the SPL just as with constant noise. The difference is that the rate of exposure and peak levels are the controlling factors in hearing damage to impact noise. Peak levels should not exceed 140 dB without protection. The Army lists it's 9mm handgun and the M16 as producing a peak noise of 157 dB (http://chppm-www.apgea.army.mil/hcp//NoiseLevels.aspx. The plugs and muffs combination would effectively reduce the exposure to 125 dB (assuming the unlikely ideal insertion of the plugs and the proper use of muffs). Should the plugs not be properly inserted protection can be as little as 10 dB resulting in an exposure of ~167 dB.

http://www.combatindex.com/mil_docs/pdf/std/1400/MIL-STD-1474D.pdf is the military standard for noise exposure including impact noise like gunfire. See pages 35, 36 and the table on 38 for impact noise exposure limits in use by the military. Here are the relevant tables extracted from the document. Note that noise from firearms will as a minimum be an X category noise after the hearing protection composite NRR is applied. The Y would be the category I would act on for a range session.
attachment.php
http://thehighroad.org/attachment.php?attachmentid=53692&d=1172121666
Click to expand...

PinnedAndRecessed,

Weren't you involved in this discussion in this thread on muffs and plugs?
http://thehighroad.org/showthread.php?t=256966&page=2&highlight=NRR
 
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I REALLY like the Peltors, I got a pair for Christmas and have worn them to the shotgun range a few times. It's a little different effect, you can't hear the shot itself, but you here the echo just after, but it's not too loud. The 85dB limit is for constant exposure during an 8-hour workday, the levels are much higher for short term exposure. I never felt like I was getting enough sound to damage my hearing (I've grown up around kind of loud equipment, you can learn to judge somewhat). Anyway, I think they're worth the money, just be sure you don't buy Bob's Dirt Cheap brand, you're hearing is one place you probably don't want to skimp on.
 
Are peltors the ones that clip high level sounds and amplify low level sounds simultaneously? Or are they the ones that clip all sound across the board at impulse, then amplify again?

I had some cheapos that would clip everything if a sound surpassed the threshold. I believe the more expensive units will continue to amplify low level noises while simultaneously clipping any sounds above the threshold?

Can someone clarify for a dummy? I didn't want to drop big bucks on a set of good electronic cans until I knew for sure.
 
Oh and one of the few thing I know about sound is that 3 dBs increase doubles the noise, 3 dBs downward halves the noise.
Click to expand...

A 3 dB rise in noise intensity is Double the noise. (88 dB is twice as loud as 85 dB. and 91 is twice as loud as 88.) 164 dB is a substantial amount of hazardous noise.
Click to expand...

Where are you all getting this information??? I checked my facts as it had been a long time and I'm forgetful at times, but 6dB increase or decrease doubles or halves perceived sound level, respectively.

There are plenty of websites and texts that explain the science/math better but
http://www.practicalpc.co.uk/computing/sound/dBeasy.htm
explains it pretty well. Or you can check some other websites if you get off on equations, but the song remains the same.

Most techs explain a 3dB increase or decrease as being 'slightly different.'
 
An increase in power and increase in perceived loudness are two different things. Power levels are calculated by strict logarithmic formula with units.

Perceived loudness is somewhat more of a psychoacoustic thing. One tone at a certain frequency will be perceived as louder than another tone at another frequency because our audible range, while good from 20Hz to 20kHz, will perceive certain frequencies keener than others (similar to how our eyes don't have a flat response curve).

A 3dB gain is a doubling in power in a base unit of Watts. I believe the 6dB figure is a doubling of voltage in electronic signal systems. A general rule of thumb for doubling of perceived loudness is about 10dB and 1dB is considered a minimal unit of perceived difference in sound levels, so a 3dB difference will, as stated, would sound "slightly different". It doesn't help that the decibel system is used in sound, electronics, radio, and a host of other systems, and they get intermixed a lot when discussing stuff. I do that too.
 
Well, I got my info from OSHA, MSHA, NIOSH, CDC, and the University of West Virginia. Still got my materials...somewhere....

Here is a NIOSH chart that shows the relation to noise and the time weighted average for exposure. The basic concept is that as noise intensity doubles (3 dB increase - see note at top of chart) exposure to that noise should be cut in half.

lookatnoise.jpg
 
Hmmm...

Very bizarre indeed! So, dB functions differently in different contexts, i.e. electric vs. audible sound? Strange...I'll have to check into this more. Just want you all to know, I'm not trying to shoot your info down...I'm just curious and maybe I'll learn something!
 
Yes, there are diffent dB for electronics, optics and sound.

Remember that they're all relative to a reference level and they're all proportionalities, but none of them are the same.

What we're looking at is dB(SPL) or Sound Pressure Level.
 
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