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Re: measuring noise levels - help needed

Subject: Re: measuring noise levels - help needed
From: "mipartitus" mipartitus
Date: Sat Sep 29, 2012 3:01 am ((PDT))
Hi Vicki,

Good sound level measurement is a science in itself, but just to get an idea 
you can in principle use a recording like you made, as long as your recording 
chain has somehow been calibrated. I did this for an Olympus LS-5 and EM-172 
capsules (in free field, no boundary rig), for all recording levels. I wanted 
to upload the resulting graph, but it seems there is no room left for new files 
in our Files directory.

So here are the raw numbers: to get the sound pressure in Pascal from the 
recorded wave file (assuming numbers range from -1.0 to 1.0, which is standard 
in most editing/analysis programs) one has to multiply the value in the 
recording with: 27.22, 7.18, 3.57, 2.32, 1.68, 1.09, 0.80, 0.55, 0.43, 0.41 for 
recording levels 1-10 MIC Sense LOW, and 3.22, 0.70, 0.36, 0.24, 0.17, 0.13, 
0.09, 0.06, 0.05, 0.05 for recording levels 1-10 MIC Sense HIGH.

There may well be a difference between the LS-5 and LS-10, and of course the 
boundary rig has an effect too, so there probably is little point in using 
these multiplication factors for this specific recording. But if you have loose 
EM-172's and an LS-5 you could give it a try (with the obvious benefit that you 
can make unattended long-term recordings, and then later measure the noisy 

If the info above is not helpful in your case, in may be of interest to people 
who use the LS-5/EM-172 combination, and who want to get an estimate of, or 
reproduce, the absolute sound levels of the auditory scenes they recorded.

Best, Gabriel

--- In  vickipowys <> wrote:
> All,
> Its spring in Australia, the birds are singing, but school holidays  
> have just started and kids on motor bikes are doing constant circuits  
> on the property next door.  One new 2-stroke bike is particularly  
> annoying.  There is a 1-minute recording of it on SoundCloud here:
> I would like to be able to get a rough estimate of its noise level  
> for legal reasons.  Does anyone know how I can estimate a decibel  
> reading from this recording?  Details of equipment are on SoundCloud.
> My legal advice is that I have 'an entitlement to the quiet enjoyment  
> of my property' and that the 2-stroke motorbike noise constitutes 'a  
> legal nuisance'.
> Being able to measure the actual noise level would be a bonus.
> Thanks in advance,
> Vicki Powys
> Australia

"While a picture is worth a thousand words, a 
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.

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