I mean how exactly they work isn't public knowledge. But we can be sure they don't just hash anything. It would be too easy to just add small amounts of noise and defeat them.
I think you misunderstood the parent comment ( or I misunderstood your reply to that). He talks about about a signature (which is pretty much what it comes down to), not a file hash as in here's a hash of the file contents. That would be meaningless.
As for the reference you provided I know how shazam works, they pretty much made a blog post about it. This is not that. Not by a long shot.
I can't think of a useful copyright matching technique that wouldn't flag different renditions of the same song. That's my point. The failures of these techniques wouldn't be hash collisions but songs that legitimately sound similar.
As for the reference you provided I know how shazam works, they pretty much made a blog post about it. This is not that. Not by a long shot.