I hear "electrical noise/current", that's the only way I can describe the sounds; sometimes it even has an irritating, repetitive rythm to it. I do have tinnitus that is not just ringing but an array of different sounds. My form of tinnitus includes the frequent repition of a line of music, which could be from a song I haven't thought of or heard since childhood, that gets stuck in my head.
I distinctly remember relaxing on the couch about 10 years ago and all of a sudden I had a head full of noise. The noise never, ever, ever goes away but the volume changes from time to time. The condition affects my sense of balance, my ability to sleep and my ability to concentrate; it can make me feel ill, exhausted, depressed and so much more. Believe me, all of this could drive a person crazy, no joke.
Any outside sound that "competes" with the noise in my head can be very grating, particularly high pitched sounds, repetitive clicking or clanking or too many sounds going on at once, as in a busy cafeteria. Some of these sounds litterally hurt my head, my teeth, and even my skin. A condition known as hyperacusis.
If any one out there finds a cure PLEASE let me know! LOL