sound meter

[Ed White]

At work I have access to a large acoustics test lab
and borrowed a portable calibrator.  My RS sound meter
was off up to + AND - 3 dB.  It varied considerably
with frequency.  At lower frequencies (<1 KHz) it read
low by 2-3 dB, at higher frequencies (>1 KHz) it read
high by 2-3 dB.  Pretty much varied all over the
place.

The message is don't get hung up on 95 dB vs. 96 dB. 
The RS meter will give you a ballpark absolute value,
and as Earl said will give you decent relative
measurements.

Ed

--- "Del K. Rykert" <drykert at localnet.com> wrote:
> My radio shack soundmeter was off by almost 3 dB
> when it was calibrated. 
>  
>         Del
>   ----- Original Message ----- 
>   From: Earl Haury 
>   To: discussion at nsrca.org 
>   Sent: Saturday, April 24, 2004 9:05 AM
>   Subject: Re: sound meter
> 
> 
>   Steve
> 
>   It matters a lot. The rules specify dB-A, so use
> the A scale. Without a calibrator most sound meters,
> even the expensive variety, are really only good for
> comparative measurements. So - use it to find what
> makes the airplane quieter but don't get fixated on
> the absolute number without a calibrated reference.
> 
>   Earl



	
		
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