I've seen and heard things before. there's been hospitalizations where for a week or so during it's been solid hallucinations. no idea what caused them, but maybe it was a drug I happened to be given both times.
I've also had more mild hallucinations that have probably been caused by eating gluten. last one was i kept hearing my dead brother crying and I was so upset I couldn't find him to help him.
it's never constant, always caused by something.