Audio isn’t unique. That was your first mistake.
Sound is just a pressure wave in air. Sound only has meaning because you’ve learnt that certain sounds have a meaning.
If you know what a sine wave looks like, that’s basically what sound is. A compression and a rarefaction in air.
That can easily be turned into an AC electrical signal because it’s the same thing, except positive and negative voltage.
That can easily be turned into a bunch of ons and offs, 0s and 1s, which is what digital is.
A digital representation of a waveform carves it up into slices. For a CD like others have said, that is 44100 times a second.
Nyquist-Shannon theory states that to recreate a waveform, any waveform, you need to sample it twice. Humans can hear between 20Hz and 20000Hz. Two samples per wavelength therefore would be 40000Hz. Add a bit for posterity and you get 44100Hz.
Nothing unique about it. Simple physics.