August 29, 2012

Headphones And Jet Engines: Both Bad For Your Hearing

Lee Rannals for redOrbit.com - Your Universe Online

You may want to crank down your iPhone earbuds a bit when listening to music, because a new scientific study says it could be as dangerous as sticking your ear next to a jet engine.

University of Leicester researchers wrote in the Proceedings of the National Academy of Sciences they have identified just how loud music may be able to lead to temporary deafness.

The researchers said that earphones or headphones on your portable music player may be able to reach levels similar to those of jet engines, leading to hearing problems like temporary deafness or tinnitus.

They said they have a better understanding of why exposure to noises louder than 110 decibels damages the ear, which could one day lead to a type of prevention.

"Dissecting the cellular mechanisms underlying this condition is likely to bring a very significant healthcare benefit to a wide population," University of Leicester researcher Dr. Martine Hamann of the Department of Cell Physiology and Pharmacology, said in a statement. "The work will help prevention as well as progression into finding appropriate cures for hearing loss."

Exposure to loud noises can strip cells that carry electrical signals from the ears to the brain of a coating called myelin sheath.

Not having this coating means the nerves will no longer be able to transmit information from the ears to the brain, according to the scientist.

The coating that surrounds the nerve cells can reform, allowing the cells to function normally again.

"We now understand why hearing loss can be reversible in certain cases," Hamann said in the statement. "We showed that the sheath around the auditory nerve is lost in about half of the cells we looked at, a bit like stripping the electrical cable linking an amplifier to the loudspeaker."

She said the effect is reversible, and after three months, hearing has recovered and so has the sheath surrounding the auditory nerve.

The researchers' findings are part of ongoing research into the effects of loud noises on a part of the brain known as the dorsal cochlear nucleus. This area is the relay that carries signals from nerve cells in the ear to the parts of the brain that decode and make sense of sounds you pick up.

The scientists have already shown in their research that damage to cells in this area causes tinnitus, which is a condition that causes that annoying ringing in your eyes after a rock concert.