Decibel Levels

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Decibel level can be harmful in alarming variety of ways

Steve Winwood is one performer who gets his share of air time on Chicago's WLIT-FM, which is meant not so much as an indictment as an indication that his brand of rock music is easier on the ears than some.

But is it really?

``You wouldn't associate Steve Winwood with loudness,'' said Dr. Ronald A. Hoffman, director of otology (diseases of the ear) at New York University Medical Center. ``But I went to one of his shows a couple of years ago and the speakers were stacked practically up to the ceiling. The sound was so loud, there was pain in my ears after 15 minutes. I had to leave.''

Of course, Hoffman might be more sensitive to such matters, but he said a growing number of his patients are young people who experience hearing loss from continued exposure to loud music in concert halls and through the headphones of portable stereo players. ``Two things affect any possible hearing impairment,'' said Hoffman. ``One is degree of loudness; the other is duration. You can experience problems with even short exposure to a very loud sound or longer contact with mid-level noise.''

Sound is measured in decibels. The scale begins at 0, which is the threshold of normal hearing. It increases logarithmically so that each 10 decibels is perceived to be twice as loud as the last. For instance, a blender or lawn mower at 90 decibels is eight times louder than normal conversation at 60 decibels.

Rock concerts can get up to 140 decibels, or the same range as jet takeoffs, construction jackhammers and firecrackers. Power drills are about 140; chain saws, 110. The subway reaches 120, and so does a loud personal stereo. Percussion instruments at the symphony might reach 130, while a video arcade can be as high as 110. City traffic noise is about 80, a noisy office might push 70 to 80, and your humming refrigerator is 40.

The government's Occupational Safety and Health Administration has set 85 decibels as a level at which continued exposure will eventually harm the hearing. Each person is different, said Hoffman, but regular exposure of more than one minute to 110 decibels can create permanent hearing loss. More than 15 minutes at 100 decibels is equally hazardous.

``Some people have a `transient threshold shift' after attending a rock concert or confronting similar loud noises,'' said Hoffman. ``They might experience a ringing or buzzing in their ears, or maybe a fullness or stuffiness, for a few hours before it goes away. Repeated exposure can become permanent.'' Hoffman said ringing in the ears or a stuffy feeling might indicate more than noise troubles. Infections, tumors or metabolic disorders of the ear can impair hearing. About 28 million Americans have some form of hearing impairment.

Noise-induced hearing loss can occur gradually and without pain, he said. Some early warning signs that might indicate the need for testing include ringing or buzzing in the ears (called tinnitus) immediately after hearing a loud noise, slight muffling of sounds after exposure (as when it is difficult to understand people when leaving a noisy area), and difficulty understanding conversation in which you hear all the words but don't comprehend all of them.

Some activists consider noise to be a vital public health issue, as well as a personal one. The League of the Hard of Hearing in New York is sponsoring its second annual International Noise Awareness Day on Wednesday, asking for a completely quiet moment at 2:15 p.m. local time as a promotion. ``We want noise to have the same status as other environmental issues affecting health,'' said Nancy B. Nadler, director of the league's Noise Center. Nadler said a growing body of research shows that noise affects even more than hearing. For example, small studies show that children who live near noisy airports show potentially higher levels of hypertension and lower levels of academic achievement.

-- Bob Condor, Chicago Tribune

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Page created April 15, 1998.
Last updated April 15, 1998.
© 1997 by the author; reproduce only for non-commercial purposes and with full attribution.