MP3s May Threaten Hearing Loss

SYDNEY, NSW - AUGUST 17: A man listens to an iPod MP3 player through earphones August 17, 2005 in Sydney, Australia. Research conducted by the National Acoustic Laboratories, to be released by the Australian Federal Government today, has found that up to a 25% of people who use iPods or other portable music devices will suffer from hearing problems as a result of listening to their players at "excessive and damaging" levels. GETTY

Loud rock music contributed to hearing loss among baby boomers, but MP3 players are poised to make the problem much worse for the next generation.

These devices, which pump music through headphones directly into the ear canal, enable the user to overcome the rumble of the subway or the drone of an airplane engine without drawing angry shouts of "turn it down!"

As a result, they easily desensitize the user to dangerously high sound levels. A CD player and a Walkman do too, but MP3 players such as the iPod pose an additional danger.

Because they hold thousands of songs and can play for hours without recharging, users tend to listen continuously for hours at a time. They don't even have to stop to change a CD or a tape.

Longer Listening, More Damage

Since damage to hearing caused by high volume is determined by its duration, continuous listening to an MP3 player, even at a seemingly reasonable level, can damage the delicate hair cells in the inner ear that transmit sound impulses to the brain.

"Studies have shown that people exposed to 85 decibels for eight hours tend to develop hearing loss," Brian Fligor, ScD, of Children's Hospital in Boston, tells WebMD. He found that all the CD players he examined produced sound levels well in excess of 85 decibels.

"Every time you increase a sound level by three decibels, listening for half as long will produce the same amount of hearing loss. The kid who cuts my grass uses an iPod. The lawn mower noise is about 80 to 85 decibels. If he likes listening to his iPod 20 decibels above that, he's in the range of 100-105 decibels. At that sound level he shouldn't listen for more than eight to 15 minutes."

But if he's like millions of other iPod owners, the boy probably listens for several hours a day, placing a large noise burden on his hearing even if he turns it down when he's not cutting grass.

Put a Lid on It

Limiting the volume of MP3 players may seem like an obvious solution.

Devices, such as the Kid'sEarSaver, claim to reduce the sound output of listening devices, such as MP3 and CD players. Inventor Tom Metcalfe tells WebMD that Kid'sEarSaver reduces sound by more than 15 decibels.

"That's enough to give parents some peace of mind," says Metcalfe.

Also, France and other European countries have enacted laws that limit the volume of iPods and other devices to 100 decibels.

But Fligor believes such efforts produce a false sense of safety.

"Capping the volume focuses on the sound level, not the dose," he said. "If you set the cap at 100, that doesn't give you license to listen all day."

Besides, as soon as those European nations capped the sound level of iPods, web sites started providing detailed instructions on how to override that limit.

Dealing With Denial

The simple fact is that young people like their music loud and seldom believe that hearing loss is a serious danger.

A recent study in Pediatrics reported that of the nearly 10,000 people who responded to a survey posted on the MTV web site, only 8 percent considered hearing loss "a very big problem."

That was below sexually transmitted diseases (50 percent), alcohol and drug use (47 percent) and even acne (18 percent). While 61 percent said they had experienced ringing in their ears or other hearing problems after attending rock concerts, only 14 percent said they had used ear protection.

Even when they believe hearing loss is a danger, many young people still refuse to turn down the music.

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