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An example...

Let me give an example of what happens:

Let's take a sine(ish) wave that is 32 samples long and goes from +10 to -10.

0 2 4 6 7 8 9 9 10 9 9 8 7 6 4 2 0 -2 -4 -6 -7 -8 -9 -9 -10 -9 -9 -8 -7 -6 -4 -2

Now, if we instead sample this wave at 2 points (every 16th sample) we get a variety of results.

Starting at position 0:
0 0 0 0 0 0 0 0 0 0 (silence)
Starting at position 1:
2, -2, 2, -2, 2, -2 (very quiet wave)
Starting at position 9:
10 -10 10 -10 10 -10 10 (full volume wave)

So the Nyquist frequency CAN reproduce a wave if you're lucky enough to to be aligned with it.

But what happens if we go to slightly more than 2 samples? To do this, we'll take every 15th sample giving us a slightly faster sampling frequency:

0, 2, -4, 6, -7, 8, -9, 9, -10, 9, -9, 8, -7, 6, -4, 2, 0, -2, 4, -6...

As you can see, we are producing an alternating pattern, but one that keeps changing in amplitude. There is no way to know exactly what the original wave looked like anymore. Given a larger (more realistic) data set, the output would go silent for extended periods of time, and this is why I say being close to 2 is very bad and why the CD does not produce high frequencies with complete accuracy.

-Bry

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