MP3 players biggest threat to hearing: study

New research announced last week finds that nine out of ten urban dwellers are exposed to enough loud noise to damage their hearing.

But rather than noisy construction sites and roaring buses and subways, the main culprits are MP3 players and stereos, according to the findings.

In a study of 4 500 New York City residents, researchers at the University of Michigan in the US found that noise from MP3 players and stereos has eclipsed loud work environments as the primary risk factor, said Rick Neitzel, assistant professor and researcher, in a statement from the university.

Still, work-related noise and loud public transit did account for some of the damaging noise levels: the study shows that one in 10 people who use public transit were exposed to noises that go above the recommended limits, just from taking public transit alone.

Yet 90 percent of public transit users and 87 percent of non-transit users are exposed to damaging noise levels mainly from using their MP3 players or stereos.

"I do think it's a serious problem, there aren't really any other experiences where we would tolerate having nine out of 10 people exposed at a level we know is hazardous," added Neitzel. "We certainly wouldn't tolerate this with another agent, such as something that caused cancer or chronic disease. Yet for some reason we do for noise."

A study published this year found that nearly one in five US teens have lost a bit of their hearing -- and the problem has increased substantially in recent years. A 2010 Australian study linked use of personal listening devices with a 70 percent increased risk of hearing loss in children.

Another study of 200 New York university students found that more than half listened to their digital music players at 85 decibels or louder -- about as loud as a vacuum cleaner. "Habitual listening at those levels can turn microscopic hair cells in the inner ear into scar tissue," one of the researchers told MSNBC.

As a comparison, speaking level is 60 decibels, a bustling street corner is 80 decibels, a circular saw is 90 decibels, a crying baby is 115 decibels, and a noise level that induces pain is 125 decibels, according to the University of Michigan researchers.

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