Music, voices, conversations with people I know... noisy damn place, it is.
I too am one of the musically impaired, (I can play the radio...) so it is truly frustrating when something original comes into my head, and I have no way of getting it out. Tried singing once, took me hours to get the cats out from under the bed
So now I just mostly sit back and enjoy the show, whatever the subconscious wants to play.