OK, just to check here, this is normal, right.
If I am lying in bed, in the dark, eyes closed, and there is a sudden sound, I see it - it is normally a pattern of black and white that flashes in my vision with the sound. Different pattern for different sounds. Always been like that. I am not sure how much that happens when eyes open and looking at stuff. It is hard to tell, but in the dark it is much more noticeable.
Wikipeda says Synesthesia