sound meter

[Ron Van Putte]

On Apr 26, 2004, at 8:34 AM, Brian Young wrote:

> Do they calibrate the meter at the NATS?

Yes.  The AMA sound meter is calibrated before use.  It is kept covered 
in the carrying case between uses and is recalibrated every hour.

Ron Van Putte
NSRCA Nats Coordinator

> --- "ed.schummer" <ed.schummer at sbcglobal.net> wrote:
>> Couldn't agree more.  Most of these meters work
>> pretty well when measuring
>> relative levels of pink noise, such as in
>> calibrating control room levels to
>> a SMPTE standard, or such.  The problem comes up
>> when there is a dominant
>> frequency that is much louder than the others, as
>> often occurs with our
>> planes.  We once tested a bunch of these meters, and
>> although on average
>> they were pretty good, I have seen as much as 6 dB
>> difference from one meter
>> to another at single frequencies, both meters
>> calibrated to the same level
>> with pink noise....
>>
>> Ed
>>
>>
>> ----- Original Message -----
>> From: "Ed White" <edvwhite at yahoo.com>
>> To: <discussion at nsrca.org>
>> Sent: Sunday, April 25, 2004 5:22 AM
>> Subject: Re: sound meter
>>
>>
>>> 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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>
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