Prolonged exposure to loud sounds is the most common cause of tinnitus. Up to 90% of people with tinnitus have some level of noise-induced hearing loss. The noise causes permanent damage to the sound-sensitive cells of the cochlea, a spiral-shaped organ in the inner ear. Carpenters, pilots, rock musicians, street-repair workers, and landscapers are among those whose jobs put them at risk, as are people who work with chain saws, guns, or other loud devices or who repeatedly listen to loud music. A single exposure to a sudden extremely loud noise can also cause tinnitus.
Another way of splitting up tinnitus is into objective and subjective. Objective tinnitus can be heard by the examiner. Subjective cannot. Practically, as there is only a tiny proportion of the population with objective tinnitus, this method of categorizing tinnitus is rarely of any help. It seems to us that it should be possible to separate out tinnitus into inner ear vs everything else using some of the large array of audiologic testing available today. For example, it would seem to us that tinnitus should intrinsically "mask" sounds of the same pitch, and that this could be quantified using procedures that are "tuned" to the tinnitus.
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.