geek things:

explaining to people how come audio clips have a sample rate of 41-48 kHz when human hearing only goes up to about 20 kHz?

it's about how you count.

"Hz" (Hertz) is the unit of a full cycle.

a full cycle goes up and then down again.

up
down

two parts.

so you need one sample for "up" and another for "down".

20,000 cycles? 40,000 ups and downs.

can't lift a weight without also putting it down again.

12 reps in a gym is 24 motions.

why 44100 Hz for the CD (Compact Disc)? so called "CD quality"?

well, first off, it's what the disc had room for. but you also want a little to go on. it has to do with math and i could go into detail there, but the important reason is that you need room for error. nothing's perfect.