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The secret of digital sound

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology

Simple gray rule

Numbers are numbers, no matter what. That's the secret of digital sound

By Al Fasoldt

Copyright © 1988, The Syracuse Newspapers

A friend of mine called the other day to get the phone number of a public-relations agency. I decided to tease him.

"Do you want a copy of the phone number or the real thing?" I asked him.

There was silence for an unexpectedly long time. Then I heard a cough.

"Well," he said, "the copy would be OK, I guess."

"Heck," I told him, "Why don't I give you the real thing anyway? Might come in handy."

"Wait a minute," he said. "What's the difference? Aren't numbers just numbers?"

Yes, I told him, of course numbers are just numbers. I explained that I was only joking. He didn't find it very funny.

So much for humor. But luckily, my nose for science had better luck than my funny bone, and I began to feel a question poking at the back of my mind.

It kept me thinking all day:

What's so special about numbers?

The answer led me on an interesting detour. I ended up finding out about a new piano.

I took the detour because the path looked more interesting than the unbending road of mathematical equations. It led me into sound.

For quite some time, I've been making digital recordings. I recorded my first digital tape a half-dozen years ago. In all those years, I never gave the process a lot of thought. I learned how it worked and that was that.

I could explain up and down, for hours on end, the principles of digital recording. But I realized on my detour past number theory the other day that I had been missing the forest for the trees.

It was the phone number joke that did it. It turned my understanding upside down. Before, I had thought of digital sound as something that was recorded using a digital process. The sound waves are turned into numbers and then turned back into sound waves.

According to the standard theory, to make a digital recording of a flute, you set up a microphone or two in front of the flute and start the recording. Later on, when you translate the numbers back into sound, you hear the flute in playback.

But suppose you don't have a flute. Can you still make a digital recording of one?

The leap of logic that we are about to make is a difficult jump. It goes against the kind of things we learned when we were growing up.

It doesn't seem normal.

So let's ask that question another way.

Suppose we each have a number. Yours is 100011001001 and mine is 100011001001.

Yes, they match. In strict mathematical terms, we know they're identical because we can switch numbers and still have the same ones.

Then does it matter where we got them?

No, of course not.

And now, get ready to jump.

Suppose you got your number by recording a few milliseconds of a flute. And imagine that I got my number by figuring out what numbers would represent a flute and typing them into a computer.

Still the same, right? Then you won't mind if I take my number and run it through your digital recorder.

I'd get a few milliseconds of flute music, just like you got. Exactly like you got, in fact.

No one would ever be able to tell my music from yours. And that means, of course, that no one could say that your digital recording was any more "real" than mine.

And that also brings me to the new piano. Ensoniq, a company in Milford, Pa., introduced a digital piano this month at the Winter Consumer Electronics Show. It creates—or perhaps we should say "re-creates"—the sound of a concert grand piano. Those who have heard it say it does its job perfectly.

Ensoniq's instrument, called the Acoustic Wave Piano, uses the same microprocessor as the Apple Macintosh computer. The computerized heart of the piano pulls numbers from its memory and adds, subtracts, multiplies or divides them to come up with the right digital signals for each press of the keys.

A digital grand piano has a lot of advantages over the kind I used to practice on. It's a lot lighter, for one thing. And it has a headphone jack. I could have used that when I was chopping Chopin at 3 a.m.

But the aspect that interests me most is the marvel of creating something out of nothing. Sure, it's only a matter of numbers, but you can't tell me that magic didn't have something to do with it, too.

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