Prolonged or loud use can lead to hearing loss, researchers
Maxing out the volume on a typical MP3 player -- such as the
popular Apple "iPod" -- for anything more than five minutes a day
can permanently damage a listener's hearing, new research says.
And listening to an MP3 in a noisy environment appears to
encourage higher-than-safe volume use, which should be avoided
altogether or offset by using noise-reduction-style earphones that
allow for listening at lower volumes, the researchers added.
Both cautionary notes were struck Thursday by researchers
presenting studies at a conference titled Noise-Induced Hearing
Loss in Children at Work and Play, in Covington, Ky. Organizers
described it as the first conference ever convened in the United
States to specifically address hearing loss among children.
The study authors said their research applies equally to a five
music players tested, including the iPod, iPod Nano, and iPod Mini,
as well as Sandisk Sansa and Creative Zen Micro players.
"What people should think about is that all personal music
players are capable of producing levels that are potentially
dangerous to their hearing, but all of them can be used in a safe
manner as well," said Brian J. Fligor, a co-author of two conference
studies and director of the diagnostic audiology program at
Children's Hospital Boston.
In one study, Fligor teamed with audiology doctoral student Cory
Portnuff from the University of Colorado, Boulder, to measure sound
levels produced by MP3 players through the stock in-ear "bud"
headphones that come with the players. The researchers also tested
optional "isolator" earphones that block background noise and
"supra-aural" earphones that sit over the ear.
After determining that all the players operated at similar volume
levels, Fligor and Portnuff sought to define uniform safe listening
recommendations. The researchers' listening advisory was set with an
eye toward established U.S. government guidelines that indicate
hearing loss can begin at volumes of 85 decibels.
With the caveat that not all people are "typical" -- with varying
levels of "tenderness" and "toughness" when it comes to hearing
tolerance -- the researchers concluded that most people can listen
to an MP3 player for 4.6 hours a day at 70 percent of full volume.
When set to 80 percent of full volume, 1.2 hours of daily
listening is the maximum, they suggested, while full volume
listening should never exceed five minutes a day when using a bud
earphone, three minutes with a noise-reduction earphone, or 18
minutes with an over-the-ear set.
The authors pointed out that the differences reflect the fact
that ear-bud style headphones deliver higher levels of sound to the
ear than over-the-ear varieties.
A second study looked at how people -- in this case doctoral
students -- actually deal with volume control in light of two
variables: background noise and earphone types. The study was done
by Fligor and Terri E. Ives, an assistant professor with the PCO
School of Audiology in Elkins Park, Pa.
In general, men listened to music at higher volumes than women.
But, overall, only about 6 percent of the study participants chose
to listen at "risky" levels -- above 85 decibels -- while in quiet
conditions. However, in noisy conditions, those students with
background-noise-reducing earphones set their volumes lower than
those with regular earphones.
About 80 percent of those study participants with non-noise
reducing earphones turned their volumes up to "risky" levels while
in noisy conditions. That figure fell to just 20 percent among those
using noise reduction earphones.
"It's very clear that the amount of background noise is the
number one thing that dictated whether or not people listened too
loud," said Fligor. "Not the kind of headphone. Except when we
provided people with an isolating earphone to isolate background
noise. That did reduce the potential risk for hearing loss, because
it did cause people to modify their hearing use to lower levels.
"So, I suggest, it's really worth the investment to get the noise
reduction earphones," he added.
That advice was seconded by Dr. Anil K. Lalwani, chairman of the
department of otolaryngology at New York University School of
Medicine and Medical Center in New York City.
"We have to be cognizant of the fact that, if we're trying to
listen to our portable devices in a noisy environment, we are
putting our ears at risk," he said. "And I would agree that those
headphones that reduce background noise are going to reduce your
risk, because you're not going to turn the volume up as high."
To learn more about preventing hearing loss, visit the
Better Hearing Institute. Posted 10-23-06 on kidsgrowth.com