I really only notice it at night, but if there happens to be a loud noise (something falling in another room, a car door being slammed loudly, etc.) I see a bright flash of light, almost at the same time as the sound.
I thought this was completely normal (IDK, a burst of adrenaline or something) but DH had never experienced it. Mind you, he also doesn't fully 'picture' things in his head, whereas I do.