Tinnitus is the term for the perception of sound when no external sound is present. Tinnitus is often referred to as "ringing in the ears," although some people hear hissing, roaring, whistling, chirping, or clicking. Tinnitus can be intermittent or constant, with single or multiple tones. Its perceived volume can range from very soft to extremely loud.
Tinnitus is not a disease but a symptom of another underlying condition – of the ear, the auditory nerve, or elsewhere.
The American Tinnitus Association (ATA) estimates over 50 million Americans experience tinnitus. Of these, 12 milion have tinnitus which is severe enough to seek medical attention and roughly 2 million persons are so debiliatetd by the tinnitus they cannot function at a normal level on a day-to-day basis.