Tinnitus (or "ringing in the ears") is sound or noise that no one but the person with the condition can hear. The noise can be constant or come in short bursts; it can last for long periods of time or go away fairly soon. The sound can be loud or soft, can change in pitch, and can be heard in one or both ears. Each person who has tinnitus can probably describe it in a different way.
It is estimated that about 10% to 15% of the population experience tinnitus.
The causes of tinnitus aren't completely known or understood and reasons can't always be found. In many cases, though, the sounds can be caused by illnesses or injuries such as:
Tinnitus, by definition, is a subjective ringing or tingling in the ear that can only be heard by the person experiencing it. The noise can be described in many ways: a humming, buzzing, ringing, whistling, clicking, throbbing, or roaring. It's often a symptom of another underlying problem (see "Causes" above for a list).
Many people with tinnitus also have lost some or most of their hearing. In most cases, it's the hearing loss that ends up causing the problem.
The worst part of tinnitus is that it can be very annoying and difficult to live with. A soft ringing sound might not be too bothersome to most, but some people hear very loud sounds over long periods of time or sounds that go away only to return just as they get used to the silence again. This can affect sleep, concentration, and quality of life.