Interesting. I can replay or simulate other people's voices (real people, obv) and can 'hear' music I know by replaying it in my mind. Of course, not perfectly if I forget the words, it might fill in with some tum-te-tum, or only recall a fragment, but it's usually playing as at source. Makes earworms very annoying, of course.

Ditto! I tend to hear my internal voice beat-boxing music rather than humming it, though...