Xref: utzoo rec.audio:8845 sci.electronics:4191
Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!comdesign!ivucsb!todd
From: todd@ivucsb.UUCP (Todd Day)
Newsgroups: rec.audio,sci.electronics
Subject: Re: Extracting Mono from Stereo
Summary: Never say never!
Message-ID: <362@ivucsb.UUCP>
Date: 1 Nov 88 18:32:31 GMT
Article-I.D.: ivucsb.362
References: <343@ivucsb.UUCP> <3902@homxc.UUCP> <353@ivucsb.UUCP> <10682@cup.portal.com>
Reply-To: todd@ivucsb.UUCP (Todd Day)
Organization: The Audio Club at UCSB, Isla Vista, California
Lines: 40

In article <10682@cup.portal.com> R_Tim_Coslet@cup.portal.com writes:
_In artical <1988Oct29.234044.15343@utzoo.uucp>
_		henry@utzoo.uucp (Henry Spencer) Writes:
_>In article <353@ivucsb.UUCP> todd@ivucsb.UUCP (Todd Day) writes:
_>>_The man wants to solve two equations for 3 unknowns:
_>>...  Can't in general be done.
_>>
_>Well, then, how come your ears solve that equation everytime you listen
_>to stereo?
_>
_>Note the words "in general".  Your brain (not your ears) applies quite a
_>bit of processing power to make sense out of what it's hearing.  Once it
_>has done so, it has enough extra information to solve the problem.  It
_>couldn't do this for random input; the extra information is available
_>only because the input "makes sense".  Duplicating this process with
_>electronics doesn't sound easy to me.

I don't think it'll be easy, either... But, the whole point is to FOOL
the ear-brain system, not duplicate it.  I wasn't offering duplication
of this system as a solution... I just offered it as example; that, yes,
one CAN solve two equations for 3 unknowns.  Note that in this system,
we have to move to the frequency domain to do it (I think this is
where we pick up that _extra_ equation that we need...).
 
_Add to this the fact that even the brain ocasionally fails to correctly
_solve this problem, and locate the sound source. This is particularly
_true for sounds generated on the plane of points equidistant to both ears...
_...you can't tell whether the sound is comming from infront, behind, above
_or below you, in this case (unless you turn you head to get it off that
_plane, or you see the source of the sound). Your electronic circuit won't
_be able to "turn its head" to get this additional info.

Does it need to?  It already "knows" that the sound is supposed to 
appear in between the speakers...

 
   /| Todd Day (805)968-9352 |\              "I go to school, but
+-+ | The Audio Club at UCSB | +-+    I never learn what I want to know."
+-+ | 926 B   Camino Del Sur | +-+     ..!pyramid!comdesign!ivucsb!todd
   \| Isla Vista, CA   93117 |/                todd@ivucsb.UUCP