I hear music in my head all the dang time! In just about everything I do, after I start, I get these really random songs playing in my head, note for note, word for word. Not only that, but when I'm in the middle of class and I'm falling asleep (I know, that's not the best thing to do, but it happens), I get to hearing several songs playing in my head.
That is, until the teacher wakes me up, or I do a bit of a head bop and re-focus again. At that moment, I'll notice how eerily silent it is. I'm probably the only person who actually does this.
When I'm dreaming, a song will play in my head with perfect replication, and it'll feel so real I can't tell the difference between the dream and a concert, until I wake up the next morning with sleep paralysis, then the tune changes (pun not intentional).
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!Data Dance!