Probably the earliest form of a list language we are given is when our parents or teachers try and tell us something and we don't hear it, and they shout derogatorily, "are you DEAF?". They can't fathom a world where being deaf wouldn't be a Bad Thing and they can't comprehend that someone just

hasn't got their attention, or, just hasn't heard them. It's the way it is emphasised as if you must be DEAF because only a DEAF person would ignore me.