Oh they do. That’s the magic. I’m just amazed that it’s possible at all.
Look at information theory. There’s a lot of redundancy in language and also in music. There’s communication involved between your own internal database of “how things should be” vs “what you actually experience” and we can fill in tremendous gaps.
So, let’s say you’re lost in the desert, 1000 miles away from anything and all you have is a shortwave radio that can only seem to get in a faint signal that’s stuck in the upper sideband but it’s shifted so it’s squealing and it’s almost impossible to understand anything.
But you can hear what sounds like a part of a note from a song you once knew.
From that, your memory can recall and reconstruct the entire song without any further input as the whole song was compressed in that tiny index that pointed to it