If you hear a constant or intermittent ringing, buzzing, or clicking for which there's no external sound source, you may be tempted to think the problem is all in your head, and that may be true. The condition is called tinnitus (TIN-IT-US). While some cases of tinnitus have specific causes such as infection in the inner or middle ear, many others exist without any discernible cause. One theory is that you have been exposed to the sound at some point and your brain keeps replaying it endlessly. Therapy centers are available to teach biofeedback techniques which allow you to ignore the sound. Of course, the first thing to do is to find an ear specialist to look for organic causes before embarking on such a course of therapy. These may include tumors, infections, toxicity caused by large doses of medication such as aspirin or quinine, or excessive smoking or drinking.