My tinnitus started after having my ears syringed by our French doctor in BKK.
I had an ear infection and the pain was excruciating.
This led to three months of sleepless nights.
Over the years the tinnitus increased in severity - cockpit noise especially on the DC10 and F100.
As far as I know there isn't a cure but there are ways of coming to terms with it.
I use an iPod with trance music or some NLP recordings to help me sleep.
I am also lucky enough to have a small waterfall outside my bedroom.
I have a close friend who didn't cope with it and lost his licence.
Good luck.