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From: howard@cpocd2.UUCP (Howard A. Landman)
Newsgroups: comp.sys.amiga,comp.sys.mac,comp.sys.atari.st,rec.music.makers,rec.music.synth
Subject: Re: Sonic Holography.
Message-ID: <1013@cpocd2.UUCP>
Date: Mon, 7-Dec-87 12:35:14 EST
Article-I.D.: cpocd2.1013
Posted: Mon Dec  7 12:35:14 1987
Date-Received: Sun, 13-Dec-87 08:28:01 EST
References: <7536@eddie.MIT.EDU> <2476@gryphon.CTS.COM>
Reply-To: howard@cpocd2.UUCP (Howard A. Landman)
Followup-To: rec.audio
Organization: Intel Corp. ASIC Systems Organization, Chandler AZ
Lines: 31
Xref: mnetor comp.sys.amiga:12100 comp.sys.mac:10817 comp.sys.atari.st:6697 rec.music.makers:1185 rec.music.synth:2133

Followup to rec.audio, which is where this belongs.

In article <2476@gryphon.CTS.COM> richard@gryphon.CTS.COM (Richard Sexton) writes:
>Sonic holograms ? Yes, a friend of mine has a Carver as well. Mighty
>impressive.

I borrowed one for a test listen.  I found that it did make a slight difference
in the sound, but only in a very small sweet spot, and not one that was
uniformly better for all material.  I was not impressed, even given the price
of $100 (used).

>Plus, there is an audio illusion I've been looking for, for quite
>a while now. Basically it is an ever increasing tone. 

Piece of cake.  The trick is to play sine waves at a certain note in all
octaves simultaneously.  Say you start at A.  Then you begin with a mixture
of A27.5, A55, A110, A220, A440, A880, A1760, A3520, A7040, A14080 and maybe
even A13.75 and A28160 if your equipment is up to it.  The relative volumes
are higher in the middle and taper off toward the upper and lower registers.

Now, you increase the pitch of each wave slightly, and adjust the volumes so
that the lower tones are a little louder, and the upper tones are a little
softer, in order to keep the "center of gravity" in frequency space at the same
place.  Repeat this until you have "gone up" one octave; at this point you can
delete the tone which is inaudibly high and insert a new tone an octave below
the lowest one.  Guess what?  You now have exactly the same signal that you
began with, and can start over.  Repeat indefinitely.

-- 
	Howard A. Landman
	{oliveb,hplabs}!intelca!mipos3!cpocd2!howard
	howard%cpocd2.intel.com@RELAY.CS.NET
	"Lather.  Rinse.  Repeat."