I guess I was somewhat lucky that I developed and was diagnosed with Tinnitus as a youngster.
(by the time I was 7 years old my mother realized that I was constantly distracted and that I often was pulling pillows around my head to try and block out the loud hissing and variable tone noise only I could hear)
It sort of became a mind over matter thing for me.
(though I don't think I really realized at that age how I began compensating for it)
I learned on my own how to tune it out and Music became my passionate and almost constant friend.
It's always there, if I stop to think about it it comes to the foreground and can drown out all other sounds, but I spend much of my time during my waking hours (when not communicating verbally with other people or talking out loud to my dogs) whistling or softly humming a song or just having one running in my mind.
Sometimes I get stuck on one song in my head for hours or even a day or two and I have to actually play out loud another. (though that may be part of my ADD)
Anyway, I sympathize.
Having to deal with constantly distracting and at times overwhelming sounds in ones head that nobody else around you can hear is quite disconcerting.