Xref: utzoo sci.physics:6297 sci.math:6009 sci.electronics:5556
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!pacbell!att!ihlpf!gmark
From: gmark@ihlpf.ATT.COM (Stewart)
Newsgroups: sci.physics,sci.math,sci.electronics
Subject: Re: noise cancellation
Summary: Yep
Keywords: anti-noise
Message-ID: <7973@ihlpf.ATT.COM>
Date: 14 Mar 89 22:17:31 GMT
References: <723@wucs1.wustl.edu> <7260@fluke.COM> <1290@wpi.wpi.edu>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 37

In article <1290@wpi.wpi.edu>, lfoard@wpi.wpi.edu (Lawrence C Foard) writes:
> In article <7260@fluke.COM> inc@tc.fluke.COM (Gary Benson) writes:
> >...
> >The idea behind "anti-noise" as you call it is that you generate an exact
> or boost certain frequencys. I wonder if there is any market for this??

As a matter of fact, I got the idea in junior high school, so I
imagine a lot of people had it.  As for marketability, there is a
British firm, I believe, that make both huge speakers and headphones
using the cancelation technique for repetitive, easily predictable,
and therefore needing very little computational power to cancel,
for the noise created by road construction equipment.  Reportedly
makes work much less destructive to workers' ears.  An interesting
use for this I was considering was to do this (assuming computational
power was available) for cars.  Sound takes a while to transmit through
the vehicle.  Place microphone(s) outside at different points,
such as near the muffler and suspension components and just generate
anti-noise for them.  Would make a Pinto sound like a Caddy, maybe?
Or a Mercedes sound like your front room?  In any case, it would have
to have some effect on the noise.  And a car already has the sound
equipment.  Essentially, this is just a computerized version of
"tailoring" a sound system for a particular make of car.  The ultimate
version of this might take into account wind noise at different points
in the car, as well as probably have a lessening effect on non-vehicle
related sounds, like nearby cars & trucks, etc., since all the noise
outside the vehicle would probably be picked up the bye microphones
and hence, compensated for.  This could also be hooked to transducers
on the frame itself, compensating, possibly, for conducted noise.
Wow, hook this with the computerized shock absorption system in
the next generation Vette, and you could have quite a comfortable
quiet rocket.

				- Mark

				G. Mark Stewart
				ATT_BTL, Naperville, Ill. ix1g266
				ihlpq!gms (312)979-0914