This sounds pretty close to how my brain processes things. I too have aphantasia, so imagination/visualization is conceptual/non-visual. The way sound plays in my head is via imaginary humming or singing by me, it never sounds as if coming from some external source. I do get rare earworms, but again, it's more of a realization that I've been humming a song for a while.

No issues with memorization, however. Brains are weird.