Why do we use 44,1 kHz frequency on CDs while we’re only being able to hear up to 20 kHz?
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If the sampling frequency is too close to the acoustic frequency, higher frequency sound waves won’t map neatly into the rigid digital containers that record their values. This causes distortion.
By sampling sound at a frequency that is at least twice the highest expected acoustic frequency, we minimize (but do not eliminate) these acoustic artifacts.
Ideally, sampling would be at least 10 times (an order of magnitude) higher than the highest acoustic frequency. Of course, higher sample rates produce correspondingly more data. So acoustic recording becomes a balance between quality and data size.
Though audio CDs sound quite good, experienced listeners can discern recording inaccuracies, especially in music with cymbals or other very high frequency sounds.
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