Experts believe that tinnitus is associated with neural (brain and nerve) injuries that affect the auditory pathway and therefore someone’s ability to hear sounds. (10) Most of the time, tinnitus is a result of a disorder that affects parts of either the outer, inner or middle ear. The good news is that the majority of cases are not linked to any serious illness, although some cases are.
Hair cells can be damaged by exposure to loud noise, which could lead to tinnitus. This can occur gradually as a result of exposure to noises over prolonged periods or may be caused by exposure to louder noises over a shorter period of time. If you are exposed to loud noises, you should always wear ear protection. Find out more about the subject on our How Loud Is Loud article and see if your job or lifestyle could be putting your ears at risk,
Tinnitus can arise anywhere along the auditory pathway, from the outer ear through the middle and inner ear to the brain's auditory cortex, where it's thought to be encoded (in a sense, imprinted). One of the most common causes of tinnitus is damage to the hair cells in the cochlea (see "Auditory pathways and tinnitus"). These cells help transform sound waves into nerve signals. If the auditory pathways or circuits in the brain don't receive the signals they're expecting from the cochlea, the brain in effect "turns up the gain" on those pathways in an effort to detect the signal — in much the same way that you turn up the volume on a car radio when you're trying to find a station's signal. The resulting electrical noise takes the form of tinnitus — a sound that is high-pitched if hearing loss is in the high-frequency range and low-pitched if it's in the low-frequency range. This kind of tinnitus resembles phantom limb pain in an amputee — the brain is producing abnormal nerve signals to compensate for missing input.
Ototoxic drugs can also cause subjective tinnitus, as they may cause hearing loss, or increase the damage done by exposure to loud noise. Those damages can occur even at doses that are not considered ototoxic. Over 260 medications have been reported to cause tinnitus as a side effect. In many cases, however, no underlying cause could be identified.
^ Langguth B, Goodey R, Azevedo A, et al. (2007). "Consensus for tinnitus patient assessment and treatment outcome measurement: Tinnitus Research Initiative meeting, Regensburg, July 2006". Tinnitus: Pathophysiology and Treatment. Progress in Brain Research. 166. pp. 525–36. doi:10.1016/S0079-6123(07)66050-6. ISBN 978-0444531674. PMC 4283806. PMID 17956816.
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