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Author Topic: Testing Gun SPL's  (Read 5514 times)

Eric Deweese

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Testing Gun SPL's
« on: July 09, 2011, 07:55:56 pm »

Hello, Subject says it all.....I have a friend who is working on some tasty gun accessories to reduce recoil and Sound levels to the person firing the weapon. He asked me if I would help him do Preliminary testing to make sure he is indeed going in the right direction. So to my question, is there anybody who knows of a decently priced HIGH SPL meter that is portable? So far the only thing that I think is in range would be the Goldline SPL 162R.....and while he said we could work out a deal for that much $$ I was wondering if there were any other options out there that would help us get the prelim testing done before he drops serious cash on final testing analysis at a lab. Any input would be appreciated thanks!

Eric
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John Livings

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Re: Testing Gun SPL's
« Reply #1 on: July 09, 2011, 08:19:09 pm »

Hi Eric,

You can start at .99 cents and go up from there.

http://itunes.apple.com/us/app/spl-meter/id309206756?mt=8

Regards,  John
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Charlie Zureki

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Re: Testing Gun SPL's
« Reply #2 on: July 09, 2011, 11:23:49 pm »

Hello, Subject says it all.....I have a friend who is working on some tasty gun accessories to reduce recoil and Sound levels to the person firing the weapon. He asked me if I would help him do Preliminary testing to make sure he is indeed going in the right direction. So to my question, is there anybody who knows of a decently priced HIGH SPL meter that is portable? So far the only thing that I think is in range would be the Goldline SPL 162R.....and while he said we could work out a deal for that much $$ I was wondering if there were any other options out there that would help us get the prelim testing done before he drops serious cash on final testing analysis at a lab. Any input would be appreciated thanks!

Eric

   Hello,

   To successfully capture accurate data for your project, you'll need a type 1, meter. It'll need the ability to be field calibratable. (you'll need a precision calibrator)
  It'll need the ability to measure PPL or Peak Pressure Levels as a standard SPL meter will not be able to capture the data fast enough, and/or some meters will average the impulse due to overloading the input.

  You'll need a meter capable of "fast" impulse measurements of up to 180 dB.

  Anything else would be useless information if this a serious project.

  I'd recommend renting a Larson Davis 800 SPL or similar spec model.

   Hammer
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Paul Dershem

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Re: Testing Gun SPL's
« Reply #3 on: July 09, 2011, 11:35:26 pm »

I wonder if, as an alternative to dedicated hardware, there's software that can be installed on a laptop at a lower cost?
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Charlie Zureki

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Re: Testing Gun SPL's
« Reply #4 on: July 09, 2011, 11:55:46 pm »

I wonder if, as an alternative to dedicated hardware, there's software that can be installed on a laptop at a lower cost?

   Hello,

   Probably, but, being a smaller market than a standard SPL meter or Dosimeter, (read: specialty equipment) there would most likely only a small amount of companies offering such gear.   (look to the Japanese Manufacturers ...or Larson & Davis (supplier to the Military, NASA, and Airport Noise Monitoring) 

   Remember, that you'd still need a quality, calibrated microphone capable of high SPLs, and the signal conditioning box (preamp and power supply) and calibrator.

   Hammer
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Brad Weber

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Re: Testing Gun SPL's
« Reply #5 on: July 10, 2011, 06:55:13 am »

You'll need a meter capable of "fast" impulse measurements of up to 180 dB.
When performing some acoustical consulting for the firing ranges and explosives range at FLETC some years ago I found several papers on the topic that suggested that 'fast' measurements were not dynamic enough to avoid affecting the measurements and even 'impulse' settings may not capture all the dynamics (slow, fast and impulse responses are defined in the related ANSI/ISO and other Standards for sound level meters).
 
 
There are many existing papers on the subject, here's a few to start:
 
http://www.rcmp-grc.gc.ca/cfp-pcaf/information/club/sou_aco-eng.pdf
 
http://www.sandv.com/downloads/0908rasm.pdf
 
http://www.guns.connect.fi/rs/308measured.html
 
http://www.elcaudio.com/decibel.htm
 
http://www.aiha.org/aihce06/handouts/rt239michalski.pdf
 

If you're looking at the effect on the shooter then it might make sense to use a dummy 'head' so that any effect of the torso, head and ear are included.  If you are looking at the effect on those some distance away you may want to measure at multiple representative locations.  Both the noise from firearms and some suppression methods can be directional so it can be important to account for that.
 
What you are trying to measure may also matter.  If you are simply trying to measure the reduction, e.g. the level dropped XdB, then how accurate the absolute value and response are may not be that important, but if you are trying to present absolute values, e.g. it went from YdB to ZdB, then you get into Type 1 or Type 0 rated meters and microphones, calibrators, etc.  Because some higher end acoustical test gear can be quite expensive, there are companies that rent it.  But it might be easier and a better value to find someone that already has the proper equipment and the knowledge of how to use it.
« Last Edit: July 10, 2011, 07:25:17 am by Brad Weber »
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Charlie Zureki

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Re: Testing Gun SPL's
« Reply #6 on: July 10, 2011, 07:47:02 am »

You'll need a meter capable of "fast" impulse measurements of up to 180 dB.
When performing some acoustical consulting for the firing ranges and explosives range at FLETC some years ago I found several papers on the topic that suggested that 'fast' measurements were not dynamic enough to avoid affecting the measurements and even 'impulse' settings may not capture all the dynamics (slow, fast and impulse responses are defined in the related ANSI/ISO and other Standards for sound level meters).

Quote
While it's true that some meters may not have the dynamic range, even with "fast" capture capabilities, the Larson & Davis, and B&K models will have the dynamic range...as I've written in my previous post.

 Also, it seems the OP is only looking to capture the highest sound pressure level and not it's frequency content, which may be enough satisfy his curiosity. But, to do any REAL development testing and verification, he'd need to spend a whole-lot more money on a FFT rig, data capture and Modal analysis rig.

   Then...he'd have to demonstrate an ability to take "good" data, verify the data through repetitive testing, be able to understand the data, and to use the tools (Modal) to make significant changes in his test samples.

  But again,..... he may just be interested in the highest pressure level.  :)

   Hammer

 

If you're looking at the effect on the shooter then it might make sense to use a dummy 'head' so that any effect of the torso, head and ear are included.  If you are looking at the effect on those some distance away you may want to measure at multiple representative locations.  Both the noise from firearms and some suppression methods can be directional so it can be important to account for that.
 
There are many existing papers on the subject, here's a few to start:
 
http://www.rcmp-grc.gc.ca/cfp-pcaf/information/club/sou_aco-eng.pdf
 
http://www.sandv.com/downloads/0908rasm.pdf
 
http://www.guns.connect.fi/rs/308measured.html
 
http://www.elcaudio.com/decibel.htm
 
http://www.aiha.org/aihce06/handouts/rt239michalski.pdf
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Eric Deweese

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Re: Testing Gun SPL's
« Reply #7 on: July 11, 2011, 01:05:08 pm »

Hey, Thanks all for the input so far.... Especially for those links!!!! I just want to clarify that we are doing just the difference in Pressure levels between non-suppressed and suppressed versions of a black rifle to the end user (the one shooting the rifle). I am very aware and told my friend up front that I do not have the equipment or capability to do in depth analysis of his product. He did ask me if I would help him with preliminary testing to narrow down his design enough to warrant sending it to be tested by the people smarter than me. That is why I was looking at reasonable priced handheld unit that I could possibly use after this project. I am very appreciative of the information I have received so far! The info I was able to dig up on the subject it seems the average SPL of non-suppressed AR's are around the low 160's.....like said this is info I was digging up online. The general consensus I am getting is that there is no way to get any reasonably reliable info with equipment that I won't have to get a loan to purchase correct??? 
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Randy Pence

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Re: Testing Gun SPL's
« Reply #8 on: July 11, 2011, 05:59:10 pm »

Hey, Thanks all for the input so far.... Especially for those links!!!! I just want to clarify that we are doing just the difference in Pressure levels between non-suppressed and suppressed versions of a black rifle to the end user (the one shooting the rifle). I am very aware and told my friend up front that I do not have the equipment or capability to do in depth analysis of his product. He did ask me if I would help him with preliminary testing to narrow down his design enough to warrant sending it to be tested by the people smarter than me. That is why I was looking at reasonable priced handheld unit that I could possibly use after this project. I am very appreciative of the information I have received so far! The info I was able to dig up on the subject it seems the average SPL of non-suppressed AR's are around the low 160's.....like said this is info I was digging up online. The general consensus I am getting is that there is no way to get any reasonably reliable info with equipment that I won't have to get a loan to purchase correct???

if the goal is simply to measure relative levels, would measuring at a sufficient distance with a lessor measurement mic work? 
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Charlie Zureki

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Re: Testing Gun SPL's
« Reply #9 on: July 11, 2011, 10:45:29 pm »

That is why I was looking at reasonable priced handheld unit that I could possibly use after this project.
 
Quote
Reasonably priced.... is a relative statement.  Look for a used L&D model 800...they were making them in the early 1990's.


 The info I was able to dig up on the subject it seems the average SPL of non-suppressed AR's are around the low 160's.....like said this is info I was digging up online.

Quote
That's why I suggested a SPL meter with "fast" PPL and that can accept levels up to 180dB.... not knowing exactly what weapon you were to test.

 The general consensus I am getting is that there is no way to get any reasonably reliable info with equipment that I won't have to get a loan to purchase correct???

Quote
No matter how many times you continue to ask the question, the answer will remain the same, you'll need an accurate meter, capable of measuring PPL, with the ability to accept high spl in a "fast" mode.   Again, check Ebay, or some of the Leasing Companies that specialize in Electronic Test gear, and don't over-look a University...they may be able to sub lease a proper meter and calibrator to you.
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