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From: pmr@drutx.UUCP (RastocnyP)
Newsgroups: net.audio
Subject: Re: Absolute phase
Message-ID: <1761@drutx.UUCP>
Date: Fri, 24-Oct-86 21:54:31 EDT
Article-I.D.: drutx.1761
Posted: Fri Oct 24 21:54:31 1986
Date-Received: Sat, 25-Oct-86 16:28:21 EDT
References: <1228@houxa.UUCP> <1366@uwmcsd1.UUCP> <1076@genrad.UUCP> <1371@uwmcsd1.UUCP> <1842@tekgvs.UUCP> <511@husc6.HARVARD.EDU>
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Organization: AT&T Information Systems Laboratories, Denver
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[?]

The psychoacoustic phenomenon I observe on my system when absolute phase is
manipulated (and it is in many albums, J.M. Jarre's "Oxygene" comes
immediately to mind, where absolute phase trickery is used) is that the
soundstage leaps from behind the plane of the loudspeakers to in front of
the plane of the loudspeakers.  So an album recorded out of absolute phase
(Sheffield Lab even produced one) has the psychoacoustic illusion that the
musicians are standing in the middle of the listening room.

But in "Oxygene", Jarre uses this technique creatively to start sounds, say
in the left channel in front of the loudspeakers (out of phase) and the pan
the sound to the right channel, invert the phase (in phase), reduce the
volume, and increase the echo content.  The result is a psychoacoustic
illusion that resembles a small model rocket launched from the left of
and in front of the left loudspeaker and traveling to a point way to the
right of and behind the right loudspeaker.  (The other sounds in this all
electronic music album are contained behind the plane of the loudspeakers.)

Pink Floyd, Dire Straits, the Cars, Kitaro, and Vangelis have also used
similar absolute phase trickery in their albums.  While absolute phase on
most stereos is not blatently obvious (the system must have a significant
amount of soundstage depth), some albums on some refined systems can
produce very interresting effects.


		Yours for higher fidelity,
		Phil Rastocny
		AT&T-ISL
		..!drutx!pmr