Okay, I have a character in a fairly typical low-tech fantasy world. At some point in his late teens, something happens that makes him lose his hearing entirely, but I have no clue how that could happen. Just about the only ways I know of to deafen someone permanently are being too close to a big explosion (might be slightly difficult with the lack of technology), brain injury (not sure how likely he'd be to survive that, even with healing spells), and illness (and I'm not even sure that would work on a young adult). If it matters, he was born already somewhat hard-of-hearing due to his mother being sick while pregnant.
I'm not very picky about how much hearing this leaves him with; I just need it to be severe enough so he has no hope of holding a conversation. Any help is appreciated, I've been stumped over this for ages!