A ringing, swishing, or other noise in the ears or head when no external sound is present is called tinnitus. Usually, it's more of a nuisance than a serious medical problem. In rare cases, it can be a sign of an underlying medical condition that needs attention. About 10% of adults in the U.S. have experienced tinnitus lasting more than five minutes.
More than 50 million Americans struggle with tinnitus, a constant ringing in the ears that ranges from mildly annoying to severely debilitating, and no cure exists. Existing treatments help some people, but none seems to work for everyone. Hearing loss affects about 500 million people, and is a major risk factor for the condition.