I think the key thing is that hallucinations seem real and outside of yourself, so hearing music inside your head doesn't count.
One time I was on a med that had mild hallucinations as a side effect. Before bed I was cutting my big toenail and noticed newsprint on my toe. I couldn't figure out how it got there. I guessed that maybe a scrap of newspaper got into my sock and moisture transferred the ink over. But the text wasn't a mirror image. It made no sense, but seemed perfectly real. And then it occurred to me that it might not be real, so I focussed for a second and it faded away right before my eyes. Until that moment, though, I was sure that the print was really there.