Rocky,
I have done sound measurements for environmental imact studies, and feel the
need to clarify what you have stated here to show why many misjudge noise
measurement readings, and their effect on the surroundings.
First the scale that is used for measurement, dbA is not linear. If you
measure a steady sound source, say an idling engine, then measure the sound
produced by TWO equally loud idling engines side by side, the reading would
only increase by ~ 4 dbA. The dbA scale is also weighted to try to represent
the acoustic sensitivity of the human ear at 1K Hz, about midrange of the
spoken voice. However it has been proven that low frequencies are what make
noise annoying (think about the thump thump thump of the overamplifled auto
sound enthusiast as he passes your house late at nite), as well as the
"raggedness" of the frequencies being generated, i.e.the difference between
music and noise. The dbA scale does not accurately measure the low end of
the frequency range as the volume increases to the point of being wildly
inacurrate in scaling loud noise perception, so quoting the dbA readings
does not reflect how much you are actually annoying the neighbors. Your wife
dropping a glass on the floor in the kitchen is not a loud noise compared to
the game you're watching on TV in the living room if measured on the dbA
scale, but it probably raised you 3' out of the chair!
Also to put your measurements into better perspective, compare them to
commonly experienced sound levels: a typical building fire alarm = 65 dba,
car passing @ 65 mph 25' away 75 dbA, hearing protection required in the
workplace 85 dbA, a loud rock concert on the dance floor 100dbA, jet plane
100' away = 130dbA.
----- Original Message -----
From: "Rocky Entriken" <rocky@tri.net>
To: <autox@autox.team.net>
Sent: Thursday, January 22, 2004 2:08 AM
Subject: Re: Arizona Motorsports Park
> Like I said, the lawyers will be busy!
>
> Sounds like a technical argument over whether all the fine points of the
> Special Use Permit were complied with.
>
> However, a death penalty without opportunity to rectify any situations
would
> (I'd guess) be looked at unkindly by most judges above the municipal
level.
>
> I also love comments of "I heard noise from the track." IMHO, the
existence
> of sound does not constitute noise. Where I live, I can hear *sound* from
my
> local roundy-round track, MORE than six miles away, if the night is clear
> and the breeze is westerly. And those are unmuffled stocker with no dB
> limits. I can hear traffic on the Interstate two miles away too. The fact
I
> am aware of the sound does not make it disturbing noise.
>
> The bad news is picky neighbors usually equate sound with noise just
because
> they do not like it. Fact is, measured from a property line (or the
> complainant's front door), the dB level of the alleged "noise" is often
less
> than the conversation between the complainant and the cop.
>
> I noticed on the AMP website (it's on the SCCA site also), there was a
98dB
> limit at 50 feet set for the Tour. That's pretty damn quiet. Last year,
> faced with a new housing development next to our playground, we used the
> occasion of a Divisional event to take dB readings. At 50 feet we had
maybe
> 6-8 cars over 100 dB (loudest, a couple at 106) out of 100. Measuring at
the
> property line of the housing development, 400 feet away, the leaves in the
> trees overhead, blown by the wind, were louder (~82dB) than the cars. When
> one of the loudest cars went on course, you'd be aware it was there but
> you'd still be able to hold a normal conversation. BTW, in taking those
> sound measurements, we did it both days of the event and chose a location
> where they'd be accelerating just off the start on day one, and
decelerating
> just after the finish on day two -- we specifically wanted the cars at
their
> noisiest point.
>
> AMP needs to be a good neighbor, but they also have to be given the
> opportunity to be a good neighbor.
>
> Rocky Entriken
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