Tinnitus

(tih-NY-tus) A disorder in which a person hears noises such as buzzing, ringing, clicking, or the sound of a pulse, when no outside sound is causing them. Tinnitus may have many different causes, and may be a symptom of another disease or condition. It may be caused by certain tumors and anticancer drugs.

Ringing sound in the ears, a common side effect of quinine treatment.