Mine is a high-pitched tone that alternates from loud to soft over the course of a few days. I need a lot of distraction on the loud days. I play the radio at night, listening to a rock station that has very few commercials, just loud enough to distract me so I can get to sleep.
I think I have a mild form of it.. probably many in my generation do with headphones and digital music that tends to be cranked up. I forgot that suspects but I remember one of my professors said that digital music doesn't sound as good as CD and whatnot, so people tend to crank up the sound in an effort to get a "fuller" experience of the music.
Doesn't really bother me, than again I'm usually good at tuning things out.