Noise related injury was a hot topic at a couple of mtgs/forum I attended last year.
Basic jist appeared to be that due to the annual audiogram at the aircrew medical then the docs can monitor the process of going deaf and provide the court with good evidence. Additionally the provision of helmets etc insinuate a compliance with duty of care.
Any suggestion that you have a hobby such as shooting, use a black & decker at weekends etc then best you have the missus video you in yr ear duffs - I was a bit sceptical but judging from some of the quoted cases sounds as though the legal stance is quite tough.
Having been a chippy before I joined seems like I'm stuffed!!