Tinnitus is a condition that causes ringing or other noises in one or both of the ears. The noise someone hears when they have tinnitus isn't caused by an external sound, and other people usually can't hear it. It affects about 15% to 20% of people and is especially common in older adults. Tinnitus is usually caused by an underlying condition, such as age-related hearing loss, an ear injury, or a problem with the circulatory system.

Source: Mayo Clinic