Sound Level meter requirements

[Dean Pappas]

So true, Earl ...
One time, when a local club had to compile this data for local authorities, the property-line noise readings were inconclusive, and showed that the ambient noise at the complainer's property line was above the standard, even if we didn't fly. For that, a calculation of the expected noise at some large distance (-6 dB for every doubling of distance above the 3meters) was the only way to show that we were an insignificant part of this guy's ambient. 96 dB @ 3M gives 65 dB @ 352 feet. I have seen 55 dB ordinances at the property line. That's close to 1400 feet away from the model.
Regards,
 

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Earl Haury
Sent: Wednesday, February 16, 2005 10:29 AM
To: discussion at nsrca.org
Subject: Re: Sound Level meter requirements


Bob
 
Lance is correct in that for noise data to be useful in a legal environment one would want to cover all the bases regarding instrument accuracy, certification, and operator qualifications. The RS meter is a poor choice in this situation, RS specifically mentions in their literature that the meter is not ANSI compliant. The RS meter is OK for comparisons - but it will drift quite a bit with temp changes. 
 
Most sound level limits imposed by ordinance deal with the noise level at the property line, usually on the order of 65 dB-A (daytime/ residential) or 68 (non-residential) max in the areas most flying facilities are located. For legal use, a club would probably be better served by a record of the sound level at the property line over the time model activity is ongoing and not. (Recording meters are readily available.) Often such data demonstrates that the modeling  contribution is a small increase over normal background noise. A search of litigation regarding modeling noise reveals that the model facility usually prevails when the property line limits are met.
 
A good source of info, including local ordinances is available at: http://www.lhh.org/noise/
 
Earl
 
----- Original Message ----- 

From: Bob Richards <mailto:bob at toprudder.com>  
To: discussion at nsrca.org 
Sent: Wednesday, February 16, 2005 7:45 AM
Subject: Re: Sound Level meter requirements

Good point.
 
For my use (making comparisons) the RS meter is fine. The club I formerly belonged to also used them for enforcing a club-imposed noise limit.
 
However, if it comes down to enforcing a local noise ordinance, a calibrated meter traceable to NIST would probably be required. I'm not sure, but I don't see why you would not be able to have a RS meter calibrated, although I am sure the measurement uncertainty would not be very good. I'm sure the calibration would probably cost more than the RS meter.
 
What are/were the circumstances of "needed in a court of law" are you referring to?
 
Bob R.

Lance Van Nostrand <patterndude at comcast.net> wrote:

Earl/John,
Our club bought a RS meter and I remember Gray taking it to a contest where 
either Earl or Mike Harrison had their Extech. The RS meter was 2 db off 
and had no calibration. We then bought the Extech and found that the 
calibration ability and the specs are needed in a court of law.
--Lance



-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20050216/76ab6a81/attachment-0001.html