Armchair Moviegoers Get Theater Sound In Their Living Rooms

It's one of the hottest trends in television. Hook up speakers to television and turn your living room into a home theater. Hobbyists have been doing it for years. Now, home theater is coming to the masses.

Companies are selling home-theater kits. Sales of speakers destined for television jumped 52 percent in the first quarter of this year compared with a year ago, according to industry figures. Sound, often overlooked in the rush to buy the biggest and brightest TV, is becoming a key ingredient in television viewing.

I've been using one such system - a $1,000 all-in-one package from British manufacturer Celestion - called HTiB (Home-Theater-in-a-Box). The experience has changed the way I think of television. The first thing you realize with a home theater is that not all television is created equal.

First, the good news. Pop in a videocassette of a recent movie or watch a prime-time show recorded in stereo and the effects are wonderfully realistic. Voices can come from the left or the right. Background noise comes from the back. The rumble of a passing truck really rumbles. Just like a real movie theater.

Commercials too become immediately more interesting because many of them are recorded in stereo. (This may not be a step forward for civilization, but that's another story.)

The bad news is that not all TV shows are broadcast in stereo. If your TV viewing is limited to sports broadcasts or reruns of older programs, such as the Andy Griffith Show, the sound is the same no matter how many speakers you use. Television content, in other words, hasn't completely caught up to the technology.

But it will.

The complete home-theater system has five speakers - three in front and two in the back - with a special sub-woofer that provides the bass. It uses Pro Logic technology from Dolby Laboratories (the same folks who brought noise reduction and a host of other advances to recordings).

The technology allows a movie or TV program to be recorded in four-channel sound, folded onto two audio tracks fit onto the film or videotape, then decoded by the viewer's receiver at the other end.

The technique involves comparing the phase of the sound waves as well as their volume. So, for example, if at a particular point in the movie, the sound tracks are in phase and at equal volume, the home-theater system using Pro Logic throws the sound to the center speaker. If the tracks are in phase but have different volumes, the chip sends the sound to the left or right speaker. And so on.

Fortunately, it's easier to set up a home-theater system than it is to understand how it works. At least, that's my experience with the Celestion HTiB. The receiver clearly indicated where all the wires were supposed to go.

The sound was fair. Brent Butterworth, editor of Home Theater magazine, is much more enthusiastic about a four-speaker system, the Ensemble IV from Cambridge Sound Works, which with a separate Sherwood receiver costs about $600.

These are the low-end products. A top-of-the-line sound system (before adding a fancy TV or anything else) can run up to $20,000 or more. Kathy Gornik, president of high-end speaker manufacturer Thiel, suggests users start out by buying two good speakers and trying those before moving up to a full-blown home-theater system.

Eventually, we're all likely to move to digital television. Dolby already has digital technology that will allow viewers to experience five channels of sound without the folding and unfolding technique of Pro Logic. The result will be another huge leap for television programming - and, of course, commercials.

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