Below are some comments regarding Mark, (I'm not Josh), Sirota's sound
questions.
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>From: Pat Kelly <lollipop@ricochet.net>
>To: "bay area team.net" <ba-autox@autox.team.net>
>Subject: Sound question Don McKenna, where are you?
>Date: Fri, Sep 29, 2000, 8:44 PM
>To the regions that actively do sound control at autocrosses:
>I'm sending this out in hopes Don McKenna will reply.
>--Pat Kelly
>Subject: Noise complaints
>Date:Fri, 29 Sep 2000 23:50:32 -0400
>From:Mark Sirota <msirota@isc.upenn.edu>
>Organization:University of Pennsylvania
> To: "Team.Net" <autox@autox.team.net>
>
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>How loud are street tires?
If the surface is smmoth asphalt and the ambient and surface temperatures
are relatively cold, street tires really "tweek" the sound meter.
>I remember many years ago in Finger Lakes
>Region, we started doing sound control. I believe our limit was
>95 dBA at 50 feet, and nobody had much trouble getting their exhaust
>systems under that limit (though a bunch of folks had to spend money,
>and many got pretty creative).
Our experience, in the SF region, over the last ten years, is that 95 dba at
100' (which is roughly equivalent to 101 dba at 50') is easily exceeded by
some prepared and modified cars and, only with creative exhaust systems can
the loudest be muffled so that they don't exceed the limit.
>
>But as I recall, the squeal of street tires was louder than that.
>Can anyone quantify how much louder?
A couple of years ago, on the asphalt lot at McClelland AF base in
Sacramento CA, Ken Mitchell asked me to sound-monitor the early run groups
due to the base management's concern that local on-base-housing residents'
would be impacted by early morning noise. The run groups had been juggled so
that "quiet' low powered stock cars, including street tire classed cars,
would run early. There were no loud exhaust or loud intake noise
measurements but, there were some, surprisingly, loud tire noises in the
cool morning groups. The loudest cars were front drivers with terminal(and
continuous) understeer on street tires. The limit we monitored to, and still
use, was 95 dba at 100'. That morning we had several cars that registered in
the area of 95 dba to 98 dba at 50' due to tire noise.
>
>For those clubs that have had noise complaints, what were the nature of
>those complaints? Were people complaining about exhaust or tires?
Our SFR experience is that the complaints come from those who have little
knowledge of the source of the sound but only that it offends them. My guess
is that the type of sound is not of much relavence but the "aggressive"
nature of the noises is what offends them.
>
>We have options on a site with a great lot, but I think it's far too
>close to residential neighborhoods to use. I'm hoping to collect
>information before we start using the site in an effort to determine
>whether it's worthwhile even to try. Any information, however
>anecdotal, is quite welcome. Good hard data is even better.
>
>Thanks!
>
>Mark
Good luck with your efforts at the new site.
Don Mckenna
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