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Re: measuring noise levels - help needed

Subject: Re: measuring noise levels - help needed
From: "vickipowys" vpowys
Date: Sat Sep 29, 2012 9:28 pm ((PDT))
I found out today that the noisy 2-stroke bikes in question are Honda  
CR85 model.  These are racing bikes.

"Wiki Answers" says this model bike is 130 dB at 12.5 metres, 124 dB  
at 25 metres, 118 at 50 metres and 'only' 114 dB at 100 metres.

So lets say the bikes (2 of them today) are riding to within 100  
metres of my property boundary in the area near my house, then that  
is 114 dB as heard at my boundary.

New South Wales government department of Environment website and  
brochures say:

"max noise level for motorcycles in areas other than public roads is  
100 dB."  [I presume they mean the output of the bike as measured  
close to the bike??  Does anyone know?]

And "it is important to operate trail bikes and four-wheel drive  
vehicles quietly when they are near properties and residential areas'.


Off-road motorcycles and other vehicles often operate with less  
effective mufflers than road vehicles, and can annoy pedestrians and  
residents when trails pass near residential areas.  Schedule 1 of the  
Regulation specifies a noise limit of 100 decibels for motor vehicles  
operating off-road.  Clause 14 of the Regulation places additional  
requirements on off-road vehicles not to produce offensive noise.

Offensive noise is defined as noise:
a.) that by reason of its level, nature, character or quality, or the  
time at which it was made or any other circumstance:
i) is harmful to (or is likely to be harmful to) a person who is  
outside the premises from which it is emited, or
ii) interferes unreasonably with (or is likely to interfere  
unreasonably with) the comfort or repose of a person who is outside  
the premises from which it is emitted.

So I am thinking these bikes are WAY OVER the legal limit, just by  
nature of the type of bike, and I should not need to be recording  
them and puzzling over difficult mathematics.

Thanks so much everyone for your comments, and please do add more!

Vicki Powys

On 30/09/2012, at 9:09 AM, Avocet wrote:

>> Using phones as SPL meters works providing you have a decent
>> calibrator and can calibrate the (external) capsule, ignoring the
>> response differences compared to a flat mic
> Unfortunately making a legal conplaint about a noise would require at
> least a certified sound level meter with the approved weighting.
> That's why I suggested claiming that the bike silencer had been
> modified which is more easily checked.
> David

"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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