Tinnitus is the hearing of sound when no external sound is present. It is usually described as a ringing noise, but in some patients, it takes the form of a high-pitched whining, electric buzzing, hissing, humming, tinging or whistling, ticking, clicking, roaring, “crickets”, “tree frogs”, “locusts”, tunes, songs, beeping, sizzling, or sounds that slightly resemble human voices or even a pure steady tone like that heard during a hearing test.  Rarely, unclear voices or music are heard. The sound may be soft or loud, low pitched or high pitched and appear to be coming from one ear or both.

Most of the time, tinnitus comes on gradually. In some people, the sound causes depression or anxiety and can interfere with concentration.  Tinnitus is common, affecting about 10–15% of people. Most, however, tolerate it well, and it is a significant problem in only 1–2% of people.