Tinnitus (from the Latinword tinnītusmeaning "ringing") is the perception of sound withinthe human ear in the absence of corresponding external sound.
Tinnitus is not a disease; but a symptom resultingfrom a range of underlying causes that can include: earinfections, foreign objects or wax in the ear, nose allergies that prevent(or induce) fluid drain and cause wax build-up. Tinnitus can also be caused bynatural hearing impairment (as in aging), as a side-effect of some medications,and as a side-effect of genetic (congenital) hearing loss. However, the mostcommon cause for tinnitus is noise-induced hearing loss.
As tinnitus is usually a subjective phenomenon, it is difficult to measureusing objective tests, such as by comparison with noise of known frequency andintensity, as in an audiometric test. The condition is often rated clinicallyon a simple scale from "slight" to "catastrophic" accordingto the practical difficulties it imposes, such as interference with sleep,quiet activities, and normal daily activities.
Tinnitus is common. About one in five people between 55 and 65 years oldreport tinnitus symptoms on a general health questionnaire and 11.8% on moredetailed tinnitus-specific questionnaires.
Tinnitus can be perceived in one or both ears or in the head. It is usuallydescribed as a ringing noise, but in some patients it takes the form of a highpitched whining, buzzing, hissing, screaming, humming, tinging or whistlingsound, or as ticking, clicking, roaring, "crickets" or "treefrogs" or "locusts," tunes, songs, beeping, or even a pure steadytone like heard in a hearing test. It has also been described as a"wooshing" sound, as of wind or waves. Tinnitus can be intermittentor it can be continuous in which case it can be the cause of great distress. Insome individuals, the intensity of tinnitus can be changed by shoulder, head,tongue, jaw, or eye movements.
Most people with tinnitus have hearingloss, in that they are often unable to properly hear external sounds whichoccur within the same range of frequencies as their "phantom sounds." This has led to the suggestion that one causeof tinnitus might be a homeostatic response of central dorsal cochlear nucleus auditory neuronsthat makes them hyperactive in compensation to auditory input loss.
The sound perceived may range from a quiet background noise to one that canbe heard even over loud external sounds. The term "tinnitus" usuallyrefers to more severe cases. Heller and Bergman (1953) conducted a study of 100tinnitus-free university students placed in an anechoicchamber and found that 93% reported hearing a buzzing, pulsing or whistlingsound. Cohort studies have demonstrated that damage to hearing (among other health effects) from unnatural levels of noiseexposure is very widespread in industrialized countries.
For research purposes, the more elaborate Tinnitus Handicap Inventory isoften used. Persistent tinnitus may cause irritability, fatigue, and onoccasions clinical depression and musical hallucinations
As with all diagnostics, other potential sources of the sounds normallyassociated with tinnitus should be ruled out. For instance, two recognizedsources of very high pitched sounds might be electromagnetic fields common inmodern wiring, and various sound signal transmissions.