Tinnitus can be perceived in one or both ears or in the head. It is the description of a noise inside a person’s head in the absence of auditory stimulation. The noise can be described in many different ways. It is usually described as a ringing noise but, in some patients, it takes the form of a high-pitched whining, electric buzzing, hissing, humming, tinging or whistling sound or as ticking, clicking, roaring, "crickets" or "tree frogs" or "locusts (cicadas)", tunes, songs, beeping, sizzling, sounds that slightly resemble human voices or even a pure steady tone like that heard during a hearing test.[4] It has also been described as a "whooshing" sound because of acute muscle spasms, as of wind or waves.[7][not in citation given] Tinnitus can be intermittent or continuous: in the latter case, it can be the cause of great distress. In some individuals, the intensity can be changed by shoulder, head, tongue, jaw or eye movements.[8] Most people with tinnitus have some degree of hearing loss.[9]
When we hear, sound waves travel through the ear into the cochlea, our hearing organ in the inner ear. The cochlea is lined with thousands of tiny sound-sensing cells called hair cells. These hair cells change the sound waves into electrical signals. The hearing nerve then sends these electrical signals to the hearing part of the brain, which analyses them and recognises them as sound.
Millions of Americans experience tinnitus, often to a debilitating degree, making it one of the most common health conditions in the country. The U.S. Centers for Disease Control estimates that nearly 15% of the general public — over 50 million Americans — experience some form of tinnitus. Roughly 20 million people struggle with burdensome chronic tinnitus, while 2 million have extreme and debilitating cases.1
Other therapies. Other treatments that have been studied for tinnitus include transcutaneous electrical stimulation of parts of the inner ear by way of electrodes placed on the skin or acupuncture needles, and stimulation of the brain using a powerful magnetic field (a technique called repetitive transcranial magnetic stimulation, or rTMS). Transcutaneous electrical stimulation has been shown to be no more effective than a placebo. In two small trials, rTMS compared with a sham procedure helped improve the perception of tinnitus in a few patients.
Subjective tinnitus is the most frequent type of tinnitus. It can have many possible causes, but most commonly it results from hearing loss. When the tinnitus is caused by disorders of the inner ear or auditory nerve it is called otic (from the Greek word for ear).[25] These otological or neurological conditions include those triggered by infections or drugs.[26] A frequent cause is noise exposure that damages hair cells in the inner ear.

Exposure to loud noise. Loud noises, such as those from heavy equipment, chain saws and firearms, are common sources of noise-related hearing loss. Portable music devices, such as MP3 players or iPods, also can cause noise-related hearing loss if played loudly for long periods. Tinnitus caused by short-term exposure, such as attending a loud concert, usually goes away; both short- and long-term exposure to loud sound can cause permanent damage.