Measuring sound differences with a sound meter

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hotair

Member
Nov 16, 2016
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ca, United States
I am trying to determine the differences is the sound level on a RAW Hm1000x in .22 cal. with the stock moderator and a couple of Donnyfl moderators. I have a Extech sl510 to do this. It's being done in a soundproof room so as not to disturb the neighbors. The problem is the meter is registering the same db, (92-93), with or without the moderator. All the settings on the meter are correct. "A" weighting, fast response, and I'm using the peak mode. It should be reading somewhere in the 70's with it on but is doesn't. I called the manufacture and the store that it was purchased from -- no help from either source. Before it's sent back I'm trying to find out exactly what's wrong. The meter is put 6 inches from the muzzle. Has anybody that has a sound meter had a problem like this? Thank you.

hotair
 
I think your expectations are about right. I too have a RAW HM1000 in .22, mine has Martin's large moderator, and it measures upper 60's to low 70's. I have a Steyr in .22, and the perception when shooting it without silencer is, very loud!. It measured mid 90's. After adding a Hogan silencer, it measures around 70 also. It sounds louder because it has more of a pop to it, rather than the rushing air sound of the others. My Daystate Regal in .22 with their moderator, also upper 60's. 
 
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I have the same issue and it is important to note that the sound meter is not in continuous measuring mode. The microphone is sampled every so often. There is a sampling rate control, usually fast or slow. Fast is about twice a second and slow is normally once per second. These type sound meters also will usually measure DBA and DBC. DBA emulates the way the human ear hears things and DBC measures long period background noise as with continuous running machinery. If you have this type of meter as I do, select DBA and Slow. You can then see the display change values about every second. Get used to that rhythm. Then pull the trigger just as the display changes. Do that a few times and average the readings. It is better to do it outside or in an anechoic chamber and have the meter on a tripod or sound reflections from walls and yourself will influence the readings.
 
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Unless you are into moderator design or fine tuning of moderator , why not just use your ears ? Neighbors or games do not judge by dB meters I believe.
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Because the human ear cannot discern differences in sound level of only a few db, occurring seconds, or even minutes apart. Also, the type of sound can be misleading when estimating its volume. For example, the Steyr rifle I mentioned has a report quality that is much more recognizable as a shot, because it pops. I wold be less comfortable using it in the yard, even if it measured at a lower level than the RAW or Daystate. With the latter two, even if the report were heard, it would not be generally identified with any type of shot. Obviously, just listening to it is the main determining factor in making a decision regarding the rifle's use in the backyard, or for stealthy hunting. The meter is mostly an academic exercise, but it is kind of interesting. 
 
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Well I tried taking the testing outside with the same results. I used a tripod to keep the meter in the same position. It's still registering low 90's with the factory moderator with two different guns. The response time in the fast mode is 125ms and the slow mode is 1ms. So far only the fast mode has been used because that's what the manual recommended. Although I found that the manual is not entirely correct. Frequency response is 31.5 to 8000hz. This meter is the extech sl510 and it measures only dbs. I am using my ears to try to hear the differences with the different moderators. It's hard to tell the 'difference' in the sound level. I can hear differences but are they actually louder or more quiet? That I don't know. Without having a second person it's a little difficult to really tell what's going on. The meter will help. If I can ever get it to work. I know this can be done with a meter. This shouldn't be such a major ordeal. If you look at the AEAC review on you tube for the RAW HM1000x .25 you will see he uses an extech model 407730 which is the less expensive model and it works just fine. He shows the meter working in the video and it reads right at 76db. There's still a possibility that the meter is defective.

hotair
 
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elh0102

What kind of sound meter are you using?

hotair
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Sounds like an easy question, but when I went to the package and paper work, I found no identity except "CEM" on the meter itself. There is no address, phone number, nothing on the meter or instructions. An internet search reveals that CEM is an Indian company, located in West Bengal, with no US contact information. It seems to be an established company in the industrial sound metering business, been in business 21 years. But it was a cheap one I bought through Amazon. Given the lack of US contacts, when it quits, I'll just toss it. But, cheap though it may be, it seems to give results consistent with information I read about regarding other measuring results. I can't remember the price, but I'm sure it was less than $50. I don't know anything about the technology, but someone above said these things meter periodically, not exactly constantly, which may explain why I get some variation. But, if I use an average of 3 or 4 readings, it is consistent. 
 
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Well, I found out why my sound meter kept reading the same even though the muzzle report was considerably different. The problem was--the sound meter was too close to the muzzle. When the meter was moved seven feet from the muzzle it worked properly and I could read the 'differences' in the sound level from one moderator to another. I also found out with the help of three of my neighbors that what one person hears to be one level of sound another person, (with good hearing), hears a different level. Everybody hears pitch and volume differently. All in all the sound meter did it's job.

hotair
 
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