I often feel better able to express myself through music than I do through language, so it's not just an aid for expression, though it's certainly that, too. I even listen to music while I'm making music.
Not loud enough to compete with what I'm playing but something in the background greases my creative wheels. I'll often get a rush of creativity while listening to a song and go to the piano while it's still playing.Wow, really? I don't think I can ever do that. There's just too much interference in my head.