One can only liken it to Chinese Water Torture-- the incessant roaring, screeching sound that exists in my head. Much like a steady drip of water, it is a constant sound that occasionally fades to the background but comes roaring back at a moment's notice.
As a kid, I had no idea what the roaring sound was in my head. I can remember many nights of tossing and turning on a school night, trying to get some sleep and wishing that I could crawl out of my head and get away from the sound. For a long time after becoming profoundly deaf in college, I was blessed with peaceful nights of sleep. In the last few years, I've had a few episodes of tinnitus that fortunately, do not last long.
There are lots of Resources on Tinnitus including some interesting pills made of botanicals that one can take to reduce it.
Most of the time, hearing aids help mask the ringing sounds, but this most recent bout won't go away even with my hearing aids in. I usually resort to hypnotherapy (something that I used when I birthed my son at home) to quiet my mind and take the focus off of the sounds. Another thing that helps is to listen to my son's music on his Ipod.
One blast of Weird Al Yankovich and the sounds are gone.