Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!uwm.edu!lll-winken!ames!ads.com!bhanafee
From: bhanafee@ADS.COM (Brian Hanafee)
Newsgroups: comp.dsp
Subject: Re: DSP for feedback control
Message-ID: <B&?$~!$@ads.com>
Date: 13 Jun 90 01:02:24 GMT
References: <539@skipper.dfrf.nasa.gov> <4762@uafhp.uark.edu>
Sender: usenet@ads.com (USENET News)
Organization: Advanced Decision Systems, Mt. View, CA (415) 960-7300
Lines: 20

In article <4762@uafhp.uark.edu> cdc@uafhcx.uucp (C. D. Covington) writes:

> [Much stuff deleted]  They call impulse response an echogram and
>measure it in European concert halls using a 9mm blank pistol!
>
When I took the course in acoustics, I was told that popping a large
balloon works much better than a pistol, because the frequency
distribution is beter.  Gunshots are somewhat deficient in the low
end of frequency.

I also want to point out that there are really two implementations
of this device (feedback assassin) that we could be discussing:
the first is a big, expensive version that sound companies would
want to buy, with complete tweaking of all the parameters.  The
cheaper alternative might be a "black box" which does nothing more
than look for frequency spikes and attenuate them.  This could be
very useful for cases when sound quality is less important than
not having feedback.

Brian Hanafee