Just to be serious for a moment, I don't visualise words, or notes for that matter: they just pop up one after another, as required. Or not. I can effortlessly play familiar arrangemts and recordings in my head, and with a little effort can play a song and/or tune with different voices and/or instruments (just about up to three) from scratch. Of course, as soon as I try to write anything down, it all evaporates, and I have to go over it bit by bit. But I can't "see" the words when I sing.

OK, that's enough seriousness.

Steve