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Originally Posted by Joeywhat /img/forum/go_quote.gif
What people tend to forget about Nyquist's Theorem just says the highest frequency that can be reproduced...it doesn't mention anything about the lower frequencies. The more times a frequency is sampled, the "better" or more accurate it will be reproduced. So at 44.1 KHz at 20 KHz frequency will only be sampled around two times...but the lower frequencies will be sampled more, and the lowest frequencies will be sampled 100's, if not 1000's of times (I didn't do that math, so I might be off a bit).
So how's that relate to higher sample rates? A sample rate of 192 KHz will sample 20 KHz more times then a 44.1 rate, thus producing a more accurate signal.
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Unfortunately your argument is flawed. If you take a 1KHz square wave (for example) Fourier shows us that this wave is made up of a 1KHz sine wave plus an infinite series of higher frequency harmonics which when all summed together make up the square wave.
Interestingly, you do need *infinite* bandwidth to produce a *perfect* square wave, since a waveform is perfectly square, then it's amplitude changes infinitely quickly. Therefore you need components of infinite frequency to produce such fast transitions. If you limit the bandwidth to say 20KHz, then the 1KHz cannot be a perfect square - it has little ripples or "ringing" on it.
Now consider my example, but instead of our 1KHz square wave, lets consider a 20KHz square wave. You need harmonics *higher* than 20KHz to try to produce the 20KHz square wave. The trouble is, we (humans) can't hear anything higher than 20KHz, and in fact usually much lower than that.
A 20KHz square wave is in fact a 20KHz sine wave (that with perfect hearing we could just about hear), plus a whole load of harmonics we can't hear. A 20KHz sine wave is just a 20KHz sine wave (obviously). i.e. the two waveforms are *identical* from the point of view of human hearing.
So humans are incapable of telling the different between a 20KHz square wave and a 20KHz sine wave. To do so would need ultrasonic hearing, which we don't have. So it doesn't matter how "lumpy" a 20KHz waveform is. We are unable to discern any of this. Anyone claiming they can *is* mistaken, unless they have the ability to hear frequencies higher than 20KHz, and no-one does!
Incidentally, although all the above is true, the output wave is filtered anyway to smooth out any ripples. So your CD player produces a pretty smooth sinusoidal output at 20KHz anyway.