Patents are a different thing, these can be applied to all kinds of small formulas, but they also have to be explicitly registered and have to go through some manual approvals etc. But this issue definitely covers similar algorithms for visual art etc.
I agree it’s probably a very grey area, but my honest believe is that the formulas can’t fall under copyright, even if they require or spawn creativity – these are both true about mathematical formulas as well. You can probably claim copyright on the resulting sound wave that you generate yourself using your own computer from this formula, but effectively anyone else can do the same and it’s unprovable whether you’ve “stolen” (copied) such music or generated it yourself, so in the result the final music is practically uncopyrightable as well.
Oh well, another copyright headache is coming