[ChuckMcM]

Off the top of my head, I'd likely try to embed a reference tone. If I couldn't do that imperceptibly I'd then look at what a discontinuous but small phase shift would look like. That would had harmonics and again, it would be a question of how perceptible were the harmonics.

[icy_deadposts]

I'm honestly not familiar with audio compression. But if its very low amplitude reference tone, isn't that the sort of thing that would get removed during compression? and if its large amplitude wouldn't it become a matter of "AI music always has a [low|high pitch] hum in the background?