Today's teenagers could become prematurely hearing-impaired, study warns

In my neighborhood, it is the immigrant parents who subject their children to continuous VERY LOUD music in their homes & cars.

http://www.eurekalert.org/pub_releases/2016-07/fda-ttc071216.php

Public Release: 12-Jul-2016
Today's teenagers could become prematurely hearing-impaired, study warns
Tinnitus, often a symptom of hearing loss, can result from constant use of earphones and frequenting very noisy places
Fundação de Amparo à Pesquisa do Estado de São Paulo

Teenagers are increasingly experiencing tinnitus, often a symptom of hearing loss, as a result of using ear buds to listen to music for long periods every day, as well as frequenting very noisy places like nightclubs, discos and rock concerts, according to a study performed in Brazil.

Tinnitus is the medical term for perception of sound that has no external source. Many sufferers describe it as a ringing in the ears, others as whistling, buzzing, chirping or hissing. A paper describing the study has just been published in Scientific Reports, an online journal published by Springer Nature.

"We found a very high prevalence of tinnitus among adolescents, and this should be seen as an early warning that these youngsters run a serious risk of hearing loss. If this teen generation continue to expose themselves to very high noise levels, they'll probably suffer from hearing loss by the time they're 30 or 40," said Tanit Ganz Sanchez, associate professor of otolaryngology at the University of São Paulo's Medical School (FM-USP) and principal investigator for the study.

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"This level of prevalence is alarming," Sanchez said. "There was a notion that tinnitus was a problem of older people, but we're seeing it becoming more prevalent in younger groups, including children and teenagers, because of their increasing exposure to high levels of noise, among other factors."

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"We found that adolescents perceive tinnitus very often but unlike adults don't worry about it and don't complain to parents or teachers, for example. As a result, they aren't seen by a doctor or hearing specialist, and the problem can become chronic," Sanchez said.

The researchers also observed that most of the teenagers who took part in the study reported risky listening habits, such as continuous use of ear buds and exposure to very noisy environments; even so, those who reported experiencing tinnitus displayed less tolerance of loud sounds.

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Tinnitus is caused by temporary or permanent damage to cochlear hair cells. Located in the inner ear (cochlea), these cells stretch and contract repeatedly in response to sound-induced vibrations.

When they are stimulated by very loud noise, such as explosions, fireworks, live pop music, or music listened to through ear buds with the sound turned up, the cochlear hair cells are overloaded and can be temporarily or permanently damaged.

Neighboring regions of the inner ear must work harder and faster to compensate for the loss of function in damaged or dead hair cells, giving rise to tinnitus, Sanchez explained.

The results of recent animal experiments conducted by neuroscientists suggest that tinnitus can also be due to impairment of hair cell synapses (neural pathways) to the cochlear nerve, resulting in reduced neural output from the ear to the brain.

Damage to these synapses due to exposure to high levels of noise can cause not only hearing loss but also neural alterations in auditory pathways that reduce a teenager's sound level tolerance.

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If these teenagers continue to use ear buds frequently and are exposed to very noisy environments until age 20 or 25, for example, the damage to their cochlear hair cell synapses will progress and they may become deaf while still relatively young, according to Sanchez.