How you lose Your Hearing
“Unless you have a shotgun go off right next to your ear, it’s difficult to pinpoint the exact cause of hearing loss,” says Ellen Lafargue, director of audiology for the League for the Hard of Hearing, in New York City.“Often it’s a combination of two factors: aging and noise.”
Genetics plays a role, too. “Two people can be exposed to the same loud noise, and one person who has a family history of hearing loss will sustain damage, while the other one won’t,” says Lynn Luethke, Ph.D., the hearing-program director at the National Institute on Deafness and Other Communication Disorders (NIDCD), in Bethesda, Maryland.NoiseThe two aspects of noise that determine how dramatically it affects the health of your ears are duration and intensity, which is measured in decibels.You can listen to 85 decibels — roughly, the noise created by a vacuum cleaner, a handsaw, or a loud restaurant—for eight hours without any ramifications, according to the National Institute for Occupational Safety and Health (NIOSH), a division of the Centers for Disease Control and Prevention. Above this, as the intensity increases by three decibels, the safe duration drops by half. So a 91-decibel sound, like a food processor, is safe for two hours, while 110-decibel noises, like a rock concert, can be potentially harmful after only about a minute and a half. (See How Much Noise Can You Take? for more decibel levels and the corresponding times.)The U.S. government recognized 30 years ago that occupational sounds, such as the din at a factory, can be harmful in the long run, so it regulates them. “But there are no standards for recreational noise, like Jet Skis, snowmobiles, racing cars, and other noisy things that are becoming more and more prevalent in our society,” Pamela Mason, a certified audiologist and the director of audiology at the American Speech-Language-Hearing Association (ASHA), in Rockville, Maryland, says. Most communities have some kind of noise-limiting ordinances. These codes can address noise coming from sources such as bars, factories, and other commercial sites, as well as loud parties, car stereos, and leaf blowers, according to Eric Zwerling, director of the Rutgers Noise Technical Assistance Center, in New Brunswick, New Jersey. “Enforcement of these codes ranges from nonexistent to spirited,” says Zwerling, who recommends checking with your local government officials to see what laws your community has.Loud noises can cause two types of hearing loss. A so-called temporary threshold shift usually happens after an event like a rock concert: You leave the stadium with your ears ringing and feeling muffled, but within a few hours they return to normal. A couple of rock concerts over the course of a year are harmless; being a groupie is not, since the number of hair cells in your ears, the final stop on a sound’s journey to the brain, is finite. Over time and with continuous exposure to loud noise, the hair cells lose their ability to heal, says Luethke.
The second type of hearing loss is acoustic trauma, a permanent condition that happens when a sound louder than 130 decibels, like a firecracker, shatters the eardrum and instantly destroys hair cells.
AgingHearing is an intricate system that declines with age. This degeneration, called presbycusis, typically hits both ears equally and is more common and severe in men. It can happen for a number of reasons: The eardrums lose elasticity; the bone joints in the middle ears stiffen, reducing the quality of the sound transmitted; or the sensory hair cells lose their vitality. In addition, the brain may not be able to process rapid conversations as quickly as it once could.
Other FactorsAccording to ASHA, there are more than 130 medications with the potential to harm your hearing. Some drugs, like aspirin, nonsteroidal anti-inflammatory drugs (such as ibuprofen), and loop diuretics (used to treat kidney diseases), can cause temporary tinnitus, or a ringing in the ears, which usually ceases once the person stops taking the medication. Other drugs, such as the antibiotic aminoglycosides (used to treat serious bacterial infections) and the chemotherapy agents cisplatin and carboplatin, can cause permanent hearing loss. “Often in these cases you’re deciding between your health and your hearing,” says Lafargue. A doctor who prescribes one of these drugs should closely monitor the patient’s hearing levels during the course of treatment.
Additional causes of hearing loss include trauma to the head; ear diseases, such as otosclerosis and Ménière’s disease; certain infections, such as syphilis; and benign tumors known as acoustic neuromas, which research suggests could be caused by loud noise.
Written by Dimity McDowell DavisJune 2006
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