Having done a certain amound of sound tech work myself, and having worked with a number of other sound techs and sound engineers, I'd have to say that most are pretty deaf, especially in the high end range. This problem is particularly noticable in sound engineers who are middle aged men.

While doing work as a sound tech, I also noticed that there are quite a few middle aged male band members who are pretty deaf, as well.

I blame it on the habit many young men have of listening to really, really loud music, which seems to lead to deafness in middle age.