Characteristics
Tinnitus can be perceived in one or both ears or in the head. 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, and in some cases, pressure changes from the interior ear. It has also been described as a "whooshing" sound because of acute muscle spasms, as of wind or waves. Tinnitus can be intermittent, or it can be continuous, in which 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.
Most people with tinnitus have some degree of hearing loss, in that they are often unable to hear clearly external sounds that occur within the same range of frequencies as their "phantom sounds". This has led to the suggestion that one cause of tinnitus might be a homeostatic response of central dorsal cochlear nucleus auditory neurons that makes them hyperactive in compensation to auditory input loss.
The sound perceived may range from a quiet background noise to one that can be heard even over loud external sounds. The term tinnitus usually refers to more severe cases. Heller and Bergman (1953) conducted a study of 100 tinnitus-free university students placed in an anechoic chamber and found 93% reported hearing a buzzing, pulsing or whistling sound. Cohort studies have demonstrated damage to hearing (among other health effects) from unnatural levels of noise exposure is very widespread in industrialized countries.
For research purposes, the more elaborate Tinnitus Handicap Inventory (THI) is often used. Persistent tinnitus may cause irritability, fatigue, and on occasions, clinical depression and musical hallucinations.
As with all diagnostics, other potential sources of the sounds normally associated with tinnitus should be ruled out. For instance, two recognized sources of very-high-pitched sounds might be electromagnetic fields common in modern wiring and various sound signal transmissions. A common and often misdiagnosed condition that mimics tinnitus is Radio Frequency (RF) hearing, in which subjects have been tested and found to hear high-pitched transmission frequencies that sound similar to tinnitus.
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