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-- by John Woram
Remember quad sound? Not the least of its problems back in the days of black vinyl was the technological challenge of squeezing four discrete channels of music into a medium limited by the laws of physics. The LP record groove could only spiral itself forward while simultaneously moving vertically and horizontally. In a three-dimensional world, this used up all the available dimensions to convey two channels of audio. Even if that little problem could be resolved, you still had to pay for more speakers and more channels of amplification. Not to mention the hefty bribes you had to offer your interior decorator, who didn't want all that extra hardware cluttering up the living room.
Since then, several forces have made it easier to go beyond simple stereo sound. For example, Dr. Ray Dolby introduced his Dolby Surround Sound to the movies. The interior decorator listened and wondered, "Why can't we have that at home?" Additional speakers were soon removed from the blacklist.
Meanwhile, digital technology did away with record-groove limitations. Even better, early experiments with quad sound eventually led to sophisticated data-encoding schemes in which sounds could be placed beyond the physical space defined by speaker location. As a rough experiment, listen to just about any recording on a conventional two-speaker stereo system. The soloist should seem to be located dead-center between the speakers, with the accompaniment spread from extreme left to right. Reverse the connection at one speaker only and repeat the test. Everything is still there, but the precise location of the soloist is probably ill defined. In some cases, the accompaniment may give the illusion of originating from a space that's actually wider than the distance between the speakers.
With no small amount of sophisticated signal processing, some of these effects can be programmed into the recording, and it's possible to create the illusion of Surround Sound from only two speakers placed up front. The catch is, much of the effect is lost unless the listener sits along a center line drawn between the two speakers. This is unlikely in many listening environments, with one notable exception: the PC. Every multimedia PC producer knows exactly where the listener is: dead-center in front of the computer monitor, and in the optimum position for experiencing the controlled effects of Surround Sound from two speakers. In this specific environment, you may not need additional speakers to enjoy some of Surround Sound's effects.
Altec Lansing's WaveCube audio steering software displays a three-dimensional soundstage with a microphone surrounded by 16 MIDI channel icons. Play any MIDI file, and each active channel changes from a number to a cartoon icon. If you drag and drop the microphone or any icon around the stage, the sound shifts accordingly. The free software is bundled with the company's Dolby Surround Sound and Dolby Pro-Logic speaker systems and allows you to position sounds wherever you want them. If you're looking for a good excuse to buy new speakers, you just found it. And when you play the latest arcade game later on and hear something going on behind you, don't turn around-you might lose points.
Copyright (c) 1997 CMP Media Inc.