That would be hearing services. Hearing is the most common. The reason is that in my generation, and before that, we used to shoot with no earmuffs, no hearing protection.
As a matter of fact, we even used to pick up the empty cartridges and put them in our ears, for goodness' sake, and shoot on the firing ranges with larger-calibre guns, as well as in enclosed ranges that are very small, smaller than this room. The noise, I can tell you, is quite incredible. Back in those days we didn't know the difference, except that later on we started to get quite deaf, some way more than others.
Hearing is the worst, though.