Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!ssc-vax!uvicctr!collinge
From: collinge@uvicctr.UUCP (Doug Collinge)
Newsgroups: sci.electronics
Subject: Nice DSP problem.
Message-ID: <617@uvicctr.UUCP>
Date: 15 Feb 89 03:42:51 GMT
References: <4104@cs.Buffalo.EDU> <1822@mit-caf.MIT.EDU>
Reply-To: collinge@uvicctr.UUCP (Doug Collinge)
Organization: University of Victoria, Victoria B.C. Canada
Lines: 31

Another in my continuing series of technical questions, and thanks to all
those who took the time to help me out in the past.

Problem: to amplify the sound in a room without feedback.

Proposed solution: Put a microphone in the room, run this signal through
a DSP Box, and into a power amp and speakers.  Ask the DSP box to compute
the impulse response of the room and audio chain so that we can predict
what the mic will hear for any given output from the speaker.  Then get
the Box to subtract that response from anything coming into the mic.
The output from the mic should then be any sound in the room not produced
by the speaker.

Now I understand that the impulse response can only be predicted with
finite accuracy and that the errors will probably lead to feedback but
presumably we can do pretty well and  get the errors below 20 dB or so.

Question:  Is this gonna work?  How much computer is this going to take
for a low reverb room like a living room? Or how about fairly reverberant
room?

Thanks again.  All you DSP freaks can look on this as a challenging puzzle...

-- 
		Doug Collinge
		School of Music, University of Victoria,
		PO Box 1700, Victoria, B.C., Canada,  V8W 2Y2  
		collinge@uvunix.BITNET
		decvax!uw-beaver!uvicctr!collinge
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