The sound itself isn't a 'sound' but a performance. Hence copyrightable. The process to create that performance could be patented.

The editing, the selection of that particular iteration as being the "right" one is part of the copyrighted material.

And it isn't merely generated by a pseudo-random process, it's generated by code written and adjusted to produce a sound within certain parameters, with variation within those parameters provided by pseudo-random perturbations.

That said, I'm sure you could also record the sound of birds chirping in the dawn chorus, with even less input from the recording individual other than selecting a particular portion of the recorded audio, and copyright that.

Any traditional performance is a pseudo-random process - it doesn't come out exactly the same way every time.

Well, the process is not pseudo-random but pseudo-randomised.

But I agree with the sentiment, that's really interesting.