Most bouts of tinnitus are brief, but for some sufferers, the condition is prolonged. Men experience tinnitus more often than women. Like so many other conditions, it becomes more common with age. It can occur in one ear or in both.

By some accounts, as many as 90 percent of all people with tinnitus also have some degree of noise-related hearing loss. Tinnitus is a problem for rock 'n' roll musicians (most famously, Peter Townshend of The Who) as well as other people who've been exposed to loud noises, such as hunters, military veterans and firefighters, who routinely hear alarms and sirens.

Beethoven is the most famous tinnitus sufferer, although his case was probably not related to damage from loud noises. He complained about a continual "whistle and buzz" in his ears as his hearing worsened in his 30s before he went completely deaf at age 44.

Experts don't really know why tinnitus is so closely linked with hearing loss. Some think cells in the parts of the brain that process sound become active spontaneously when they aren't receiving enough input from the ear and its nerves. It's somewhat like the phantom limb pain experienced by amputees.

In some cases, tinnitus results from stimulation of the cochlea, the coiled structure inside the ear that contains the hair cells. Hair cells translate sound vibrations into nerve signals, allowing us to hear. Sometimes the hair cells spontaneously vibrate on their own, creating noise. Or twitches in the muscles near or within the ear might cause a clicking sound. And turbulent blood flow through the blood vessels near the cochlea can create a whooshing noise that only you can hear.

More commonly, tinnitus is caused by some kind of damage to the ear, the hearing centers of the brain, or both. Examples include noise-induced hearing loss; a congested or abnormally open eustachian tube; an excess of the fluid in the middle ear (Meniere's disease); or - very rarely - a tumor of the nerve connecting the ear to the brain (acoustic neuroma).

Ear infections, Lyme disease and meningitis sometimes cause tinnitus. So can certain medications, including aspirin and some types of antibiotics and chemotherapy treatments.

But for most people with tinnitus, the cause is unknown. As many as half of those with tinnitus also cope with depression. In some cases, tinnitus contributes to depression, but in others, it might be a symptom. Some people report that stress worsens their tinnitus.

In a few cases, treatment can reduce the noise. For instance, surgery can repair the kinks and bulges in blood vessels that cause turbulent blood flow. If the problem is twitchy muscles, injections of the muscle-relaxant Botox might help.

Other therapies aim to get people to ignore - or at least be less annoyed by - tinnitus instead of trying to attack the cause. Masking devices, which look like hearing aids, produce a low-level sound. By tuning into the masking device, the ear and the brain seem to forget about tinnitus - at least temporarily. But the devices don't work for everybody, and for some, they make things worse.

Some people with hearing loss and tinnitus find that both problems improve after they get a hearing aid or have a cochlear implant (a small, implanted electronic device that helps some deaf people hear). Others find that their tinnitus symptoms improve somewhat when they cut down on caffeine and alcohol, reduce the amount of fat in their diets or quit smoking. Another tip is to use a "white noise" machine, since background noise tends to drown out tinnitus. Reducing stress, with techniques such as yoga, visualization, and regular exercise, might help. If your own stress-reduction techniques don't work, consider biofeedback or hypnosis. Ask your doctor to recommend qualified practitioners.

From the the faculty of HARVARD MEDICAL SCHOOL. Submit questions at www.health.harvard.edu/adviser.

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