From: "Phil Allison"
References: <email@example.com> <$cHaBGAC4uC+Ew2G@jmwa.demon.co.uk>
Subject: Re: Sound cancellation technology?
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Date: Fri, 27 Dec 2002 10:03:50 +1100
NNTP-Posting-Date: Fri, 27 Dec 2002 09:54:19 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"John Woodgate" wrote in message
> I read in sci.electronics.design that Phil Allison
> wrote (in ) about 'Sound
> cancellation technology?', on Thu, 26 Dec 2002:
> >"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 ??
> Well, your 60 dB appeared out of the woodwork, and such an extreme level
> of cancellation may not be necessary.
** It is if you want to get to sleep. Traffic noise and barking dogs
can be at up to 85 dBA SPL inside the room. Supression to near the
ambient ( 25 dBA SPL) is the desired goal.
The answer, anyway, is, with great
> difficulty and at great cost, as I said.
** You said it could be done - please outline how ?