From: "Phil Allison"
References: <email@example.com> <firstname.lastname@example.org>
Subject: Re: Sound cancellation technology?
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Date: Fri, 27 Dec 2002 17:42:55 +1100
NNTP-Posting-Date: Fri, 27 Dec 2002 17:33:12 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Richard Steven Walz" wrote in message
> In article ,
> Phil Allison wrote:
> >"John Woodgate" wrote in message
> >> I read in sci.electronics.design that Lady Liberty
> >> wrote (in
>> .124.0.13>) about 'Sound cancellation technology?', on Wed, 25 Dec
> >> >Fine but not my question. Could someone please answer the actual
> >> >
> >> >
> >> OK, it is almost certainly possible, but would be very costly, not
> >> necessarily in terms of equipment but in the custom DSP software
> >> required.
> > ** Really ?
> > How do you cancell by a factor of 60 dB *any* noise that intrudes
> >into a bedroom ? This may include barking dogs next to the window, road
> >traffic noise of all sorts at close range, aircraft noise, neighbours
> >activity impacting the floor/ceiling interface with deep, powerfull sub
> >sonics etc, etc.
> > These create sudden and disturbing noise in the room at almost any
> >frequency 60 dB or more above ambient with attendant internal
> >and varying phase at any point and arriving from any of dozens of sources
> >and directions ??
> > .................... Phil
> If you mapped transducers onto the entire areal perimeter of the room on
> its walls where sound enters, it is theoretically possible by Kirchhoff
> diffraction analysis to counter any sound energy entering the room using
> Kirchhoffian wavelet inversion. But, of course, that's a real PITA.
** Betcha the "Liberty Lady" wants a little gadget she can carry around
to use in noisy motel rooms.