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A man's ear.

You risk damaging your hearing and eventually suffering hearing loss if you don't wear earplugs at concerts, says U medical resident David Opperman.

Concert accessories: earplugs are in

From M, winter 2006

"If you go to concerts, don't forget to take your earplugs," advises David Opperman, medical resident at the University of Minnesota's otolaryngology department. "If you don't, you risk damaging your hearing and eventually suffering noise-induced hearing loss."

In a study to determine the benefits of earplugs, Opperman and his fellow U researchers assigned 29 men and women--ranging in age from 17 to 59--to sit in a variety of seats while attending concerts featuring heavy metal, pop, or rockabilly music. Two people were placed in each location: front row, stage-left, stage-right, and far from the stage. One person in each of those locations wore earplugs while the other did not.

Before the concerts, the study participants all had normal or near-normal hearing thresholds (the softest sound you can hear on an audiogram) based on the results of a hearing test called an audiogram. After the concerts, when audiograms were given again, 64 percent of those not wearing earplugs had significant hearing threshold shifts. They couldn't hear a sound as soft as they could before the concert, compared to 27 percent of those wearing earplugs. The study found that the shifts occurred regardless of seat location or type of music. In addition to the audiograms, the researchers used a new mathematical system developed by study coauthor Robert Schlauch, an associate professor in the Department of Speech-Language-Hearing Sciences, to measure the incidence of the hearing threshold shifts.

Which earplugs are best?

According to the National Institute for Occupational Safety and Health, the best hearing protector is the one that is comfortable and convenient--because only then will you wear it every time you're in an environment with hazardous noise. Your choices include expandable foam plugs, which can be rolled into a tube to conform to the shape of your ear canal; pre-molded, reusable plugs made of silicone, plastic, or rubber that come in "one-size-fits-most" or several sizes; and canal caps, which resemble earplugs--some have headbands that can be worn over the head, behind the neck, or under the chin.

Although there is no clear definition of how long a temporary shift can last, if the threshold difference does not recover, irreversible cochlear damage has likely occurred, resulting in a permanent threshold shift. Such permanent threshold shifts are often accompanied by other common symptoms of hearing dysfunction including tinnitus and frequency distortion.

When the researchers measured sound levels at the concerts, they found the maximum was 125 decibels. Prolonged exposure to noises of about 85 decibels can damage hearing, according to studies.

"It's not just the loudness of music at concerts that puts your hearing at risk--crowd noise can also have a big impact," says Opperman, lead investigator of the study. "We observed the surrounding noise from the crowd was significant."

To listen to an audio vignette on the earplug research, click on University of Minnesota Moment. University of Minnesota Moment is a daily radio features highlighting University expertise on a wide range of timely topics.