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Old August 30, 2012, 03:54 PM   #1
chewie146
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Decibel Meter on the Cheap?

Ok, so here's the situation. I've googled and googled and haven't found an answer to my question. There's supposition and arguing, but nothing definitive. I have 3 firearms chambered in .357/.38 special. What I'm curious is what effect the barrel length will have on different powders, using the same cartridge, albeit within different firearms. I want to know how the noise levels will differ between them This is the only forum I could think of to post this question. Where could I get a decibel meter that could measure these kinds of sounds for the least money. If I find anything useful, I'll make sure to send the results out.
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Old August 30, 2012, 03:56 PM   #2
insomni
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ebay?
http://www.ebay.com/itm/Sound-Noise-...item20c94997ce
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Old August 30, 2012, 03:57 PM   #3
Steviewonder1
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If you have an iPhone there are a few sound meters and sound pressure meter apps out there.
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Old August 30, 2012, 04:42 PM   #4
chewie146
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I don't have an iPhone, but my friend does. Maybe he'd help. Do you know how accurate any of these are? I'm not talking university-level experimentation, but I'd like to be reasonably right.
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Old August 30, 2012, 05:21 PM   #5
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Radio Shack.

50 clams.

http://www.radioshack.com/search/ind...vel+meter&sr=1

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Old August 30, 2012, 06:16 PM   #6
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I had a Radio Shack meter and it worked pretty well. I did some sampling and then had an Industrial Hygienist come in and my cheap meter was dead on to his more expensive model. So, it should work for what you need, but I would be careful using it for a hearing protection program.
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Old August 30, 2012, 09:52 PM   #7
Pointshoot
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That meter goes to 130 dB and firearms register considerably higher:

http://www.freehearingtest.com/hia_gunfirenoise.shtml

I have no idea how far away the firearms were from the test instruments, but if it were me I'd keep this in mind. I'd get some distance from the muzzle of the gun, at least the first times I tried using the sound meter.
And if you haven't already done so, I'd study up on the nature of sound measurements. A 10db difference in sound level is considerable.

Please let us know how it all works out. I'd be curious to hear how a .357mag and 45colt compares as measued by that meter.

Last edited by Pointshoot; August 31, 2012 at 11:39 AM.
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Old August 31, 2012, 08:41 AM   #8
chewie146
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Yeah I'm going to have to do some shopping around. Maybe there's a geek trade show or something around here. It's a geek town, and I'm a certified geek. I'm hoping to find one that not only goes higher but is capable of measuring impulse noise. Most sound meters measure repeated noises, etc. You can measure the peak of a series of gunshots, but I'm hoping to use a contender. Maybe the guys at silencertests have a line on a good one.
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Old August 31, 2012, 08:42 AM   #9
wogpotter
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You can rent dB meters & the required callibrator, without which the data means nothing, from most industrial safty suppliers.
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Old August 31, 2012, 09:00 AM   #10
chewie146
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Yeah I'm looking at that too. There's a franks hardware that services the lab around here. They may have one. I think that might be the way to go. I'll see where I can rent one and do it in a one-day shoot.
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Old August 31, 2012, 11:09 AM   #11
wogpotter
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Don't forget you need to actually map the sound out, not just take 1 reading & call it good.
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Old August 31, 2012, 11:47 AM   #12
chewie146
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I planned on shooting quite a bit for each test. Say 5 readings?
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Old August 31, 2012, 11:47 AM   #13
Pointshoot
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This sounds like a really interesting project.

After experiencing a little high frequency hearing loss while hunting geese (it was in the winter & my stocking cap somehow interfered with the seal on my electronic ear muffs) - - I've been very aware of the effect of gun blast. Its pretty tough to hunt or be at your best in a defensive situation, if youre deaf.
Among my favorite handgun cartridges are the 45 Colt and 44 Special because they get the job done very well, without a lot of blast or fuss.

I look forward to your results.

P.S. - - it would be interesting to test some ammo advertised to offer lower flash and blast, to see how they actually measure up. I like the Speer Gold Dot 45 Colt commercial load. Modest velocities and muzzle blast - but they open up at slow speeds and penetrate well.
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Old August 31, 2012, 11:53 AM   #14
chewie146
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That would be something interesting to incorporate as well. Speer gold dot SB vs. gold dot "vanilla".
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Old August 31, 2012, 03:09 PM   #15
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Sorry I guess I wasn't clear when I said "map them".

I didn't mean take several reads & average them, I meant you need to take several readings at different points & then average those readings so you get an idea of where each position rates for noise. Usually the meters have some kind of attachment so you can put them at different points in front of, to the sides of & behind the gun safely. Then you actually draw a "map" of the sound patttern. If you don't do this you'll never know "how loud" it is because the percieved loudness will vary with location & distance.

You should end up with something like this, distance from center is "loudness" & directioin is from the source to the meter's mic. Yours won't be this complex as you're just measuring one parameter, overall noise.
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Last edited by wogpotter; August 31, 2012 at 03:18 PM.
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Old August 31, 2012, 04:01 PM   #16
chewie146
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Actually, I was more concerned about perceived loudness from the point of the shooters ears. So maybe taking readings on either side of my head. The only thing is trying to replicate the ear, because that funnels sound back into the ear canal. Downrange I could care less how low it is.
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Old August 31, 2012, 10:35 PM   #17
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Many cheaper meters will not react quick enough or go high enough in scale to measue gunshots. Expect some varying results if you buy and use a cheap meter just due to the instrument itself.
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Old September 1, 2012, 07:58 AM   #18
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You could just do that. The surroundings will effectthe recorded intensity as well, so factor that in when you test & take the readings in the actual environment you'll use most.
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Old September 3, 2012, 06:27 PM   #19
chewie146
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I'm thinking about just renting one for a week or weekend. Maybe this is a good project for the winter when the days are nice and still around here. No wind, etc. Cold air would probably make a difference in how the sound travels, but would it affect the sound reaching the mic on the meter? In cold air, the speed of sound is lower, correct? I've got a fair bit of research to do before I get all this underway.
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Old September 4, 2012, 08:01 AM   #20
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Speed isn't going to be a factor, just amplitude (volume).
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