This is a really interesting question. If I were a researcher, I’d try to go chase this topic, since it seems to be fairly quantifiable.

Like Mudskipper, I can replay music in my head but it has a few caveats: I don’t really process the instruments… I remember the pitch/volume/etc but primarily of vocals. I also replay with the original singer’s voice and not my own. Replaying a few songs in my head now and I can’t even focus on the instruments if there were vocals unless they are critical to how the song works, like a bass drop. If I try to replay music that is instrumental, I get verbal recreations, like someone performing the song acapella. If i focus hard, I can hear instruments instead, but that requires thinking about it. This matches how I ‘sing along’ with instrumental pieces in otherwise verbal songs. It might just be that the backing music isn’t retained, so I can remember the melody, but not, say, a bass line unless the bass is being highlighted.

Are there people who CAN’T replay music in their heads? Are they immune to ‘ear-worms’ or do they just perceive it differently?