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How the imp in me made the sound fall down

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology

Simple gray rule

How the imp in me made the sound fall down

By Al Fasoldt

Copyright © 1990, The Syracuse Newspapers

I've heard surround-sound demonstrations for years, and they've usually left me totally unimpressed.

So what if the sound track of a movie bounces around the room? No matter how clever the recording engineer is, I'll never be convinced that the good guys are in front of me and the bad guys are behind me just because I can hear them firing their six-shooters from behind my head.

Movies can't be realistic unless they pull a fast one on you. They have to fool your eyes and ears.

That means they have to be viewed on a screen that's big enough to fill most of your field of view, and it means the sound has to seem like it's coming from the screen—more or less.

The first requirement can be met easily these days. Projection TVs are getting better all the time, and the best of the new models have amazingly sharp, bright pictures.

But it's the "more or less" part of the second requirement that causes difficulty. If the sound doesn't seem to come from the screen, your ears won't be fooled at all. Something inside your brain sends out a message that says, "Hey, there's a couple of loudspeakers behind your head, pal."

That's the wrong message when you want realism. You want your brain to say, "Wow! Golly! Watch out! You'd better duck, dude!"

So the only way to do that is to keep your ears from knowing what's really going on. They have to hear just the front speakers in the surround-sound system—but they have to sense what is coming from the rear.

If the rear speakers are loud enough to be heard by themselves, they get in the way and ruin the effect.

That's the mistake that many hi-fi and video stores make when they set up demos of surround sound. And no doubt many listeners repeat the mistake when they adjust their front and rear sound levels at home.

So you can imagine that I was less than enthusiastic the other day when my videophile brother invited me to watch one of the "Indiana Jones" movies on his new home theater system.

He has a modern projection TV with a screen nearly 4 feet from corner to corner. On each side are large loudspeakers with powerful woofers. They can make walls shake a block away.

At the back of the room were two tiny speakers, so small that they could have been the kind you plug into your Walkman. Were they hi-fi? Well, maybe, but not the kind of hi-fi I was used to. I like big sound; just ask my neighbors.

I sat in an easy chair toward the rear of the room. The TV came to life and the movie began. The picture was big and vivid, and the sound track—in stereo, of course—was stunning. It was the best sound I'd ever heard outside a theater. (And it was better than I'd heard in many old movie houses, too.)

Of course, I said to myself, this isn't surround sound, even though there are two little speakers behind me. All the sound is coming from the front.

But at my right, on a little table, was a surround-sound controller. It was turned on.

The imp in me began hatching a plot. I waited until my brother wasn't looking and then pushed the button marked "power" on the controller. The little red LED next to the power switch faded and died.

Suddenly the sound fell down. I'm not sure if I know how to explain it any better. All of a sudden the sound was ordinary and flat. It didn't come from the screen any more; it came from the two loudspeakers at the front of the room.

My brother gave me an evil look. I smiled as if nothing had happened and turned the little switch back on.

It took a half-second or so for the circuits to stabilize, and then the room came back to life. The sound had width and height and depth to it. And yet I still couldn't hear the speakers behind me.

They were loud enough to supply the little cues that let my brain know how "big" the sound was—how solid, you might say—and yet they weren't loud enough to be heard by themselves.

It was a perfect demonstration. My brother even had popcorn and soda. I was hooked.

As soon as I got home, I went shopping and picked up two of the essentials, with only a few more items still needed.

I bought the popcorn and the soda. I already have a big TV, so all that leaves is the surround-sound system.

Santa, I know this is a little bit early, but if you could swing it, I'd like….

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