I'm really sensitive to this (I used to be even more, but, I'm guessing, after years of going to disco's and rock concerts, my earning lost some of its sharpness - on a side note, I used to be able to recognize basically anyone's voice - even distant acquaintances - and lost some of that with time, probably because of this reduction in hearing.).

It's really ,really distracting and enervating. Specially, because most people around you can't ear it and think you are just being picky. Imagine a TV, and that noise is there all the time and you can't watch anything in peace because you keep earning that high pitched noise in the background.