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# Section 2.2: Analog Versus Digital

The distinction between analog and digital information is not an easy one to understand, but it’s fundamental to the realm of computer music (and in fact computer anything!). In this section, we’ll offer some analogies, explanations, and other ways to understand the difference more intuitively.

Imagine watching someone walking along, bouncing a ball. Now imagine that the ball leaves a trail of smoke in its path. What does the trail look like? Probably some sort of continuous zigzag pattern, right?

Figure 2.4  The path of a bouncing ball.

OK, keep watching, but now blink repeatedly. What does the trail look like now? Because we are blinking our eyes, we’re only able to see the ball at discrete moments in time. It’s on the way up, we blink, now it’s moved up a bit more, we blink again, now it may be on the way down, and so on. We’ll call these snapshots samples because we’ve been taking visual samples of the complete trajectory that the ball is following. The rate at which we obtain these samples (blink our eyes) is called the sampling rate.

It’s pretty clear, though, that the faster we sample, the better chance we have of getting an accurate picture of the entire continuous path along which the ball has been traveling.

Figure 2.5  The same path, but sampled by blinking.

What’s the difference between the two views of the bouncing ball: the blinking and the nonblinking? Each view pretty much gives the same picture of the ball’s path. We can tell how fast the ball is moving and how high it’s bouncing. The only real difference seems to be that in the first case the trail is continuous, and in the second it is broken, or discrete. That’s the main distinction between analog and digital representations of information: analog information is continuous, while digital information is not.

Applet 2.1