Tuesday 16 April 2013

Short-term hearing loss is body's way of protecting itself

Short-term hearing loss after a loud rock concert might not be all bad, according to research showing this is the body's way of protecting itself.
Professor Gary Housley's research debunks a number of myths, including the idea that temporary hearing loss after a rock concert indicates damage.
"It may explain why we lose our hearing for hours or days after we have been exposed to a rock concert or listen to music at high levels using our personal music players," says the University of NSW professor whose paper is published in the journal Proceedings of the National Academy of Science (PNAS).
Prof Housley cautions that continued loud noise can lead to irreversible damage through the loss of high-frequency hearing.
"Our research shows that the ear can adapt to high noise levels and keep operating. But there is a catch - because our hearing adjusts, we think the sound has a lower volume than it actually has and we can easily exceed the capacity of the ear."
He says safe workplace legislation specifies the upper limit of noise exposure is 85 decibels for eight hours a day and 97 decibels for 30 minutes, as sound intensity doubles every three decibels.
The sound in a typical nightclub can be 95 to 105 decibels.
"Other research shows people are regularly listening to personal music devices in excess of 100 decibels."
There are no restrictions on noise levels from personal music devices in Australia, but in the European Union they are pre-set at 85 decibels.
Prof Housley and researchers from New Zealand and the US found that as sound levels rise, the cells in the cochlea release a hormone which causes a temporary reduction in hearing sensitivity.
His team found that reversible hearing loss is a physiological adaptation mechanism.
Now the team are hoping to find ways to better protect the ear against noise in loud environments.

Phil Chambers note:
The limits above apply to Australia.
The work does agree with the concern that SSS have always had that we face a major problem in decades to come as people who are now young and whose hearing is being impaired by loud earphones have the added loss of hearing that is related to age.

Source: The Australian 16th April 2013

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