Noise-Induced Hearing Loss Escalating

The generation that mocked their elders with "If it's too loud, you're too old," is singing a different tune. Only they can hardly hear themselves.

Noise-induced hearing loss is escalating and not just among senior citizens. Eighteen percent of Baby Boomers have hearing loss; meanwhile, 7.4 percent of Generation Xers have damaged ears, according to the Virginia-based Better Hearing Institute. Overall, most of those who say "what?" so often that there's clearly a problem (65 percent) are below retirement age.

Excessive noise is the leading culprit, and audiologists suspect that the problem is fueled by the proliferation of devices with amplified sound, namely cell phones and MP3 players, such as iPods, which send noise directly into the delicate ear canal.

"We're starting to see hearing loss in young adults that we expect to diagnose in middle-age adults," said Robert Novak, director of clinical education in audiology at Purdue University. Novak noted that many people, especially college students, have objects stuck to the side of their heads at all times. "Their ears have very little quiet time to recover from noise exposure," he said. "Often, listeners play music too loudly to drown out the background noise."

Sound is created when noise beats against the eardrum and the vibrations stimulate nerves deep inside the ear. There, fine hair cells called cilia convert the vibrations into nerve impulses, which are transmitted to the brain.

Over time, continued exposure to noise of 85 decibels or louder will destroy some of the fragile hair cells in the inner ear that respond to high pitches. One study of portable compact disc players found that volume ranged from 91 to 121 decibels. Earphones that fit inside the ear increase the volume by 7 decibels to 9 decibels.

In Europe, iPods are legally capped at 100 decibels, but there is no U.S. limit on the volume of personal music devices.

In general, the louder the noise, the less time it takes to lose your hearing. The ears are designed to hear a whisper in a forest (30 decibels), but they end up dealing with a lawnmower (90 decibels), which can damage hearing after eight hours of exposure. Stereo headphones (set at 100 decibels) can harm ears in two hours, while a rock concert (120 decibels) wreaks havoc in just 7.5 minutes, according to the Sight and Hearing Association.

Concertgoers or construction workers are most familiar with a form of short-term hearing loss called temporary threshold shift. Symptoms include a buzzing or hissing noise, or the feeling that everything sounds like it's underwater. Only noises above a certain level can be heard.

Normal hearing usually returns overnight, but the fragile hair cells have been damaged. If lengthy or repeated, the result is permanent hearing loss.

"It's wonderful to use personal-amplification systems, but check your genes," said Carol Rogin, senior director of the Better Hearing Institute. "Hearing loss that is age- or noise-related can run in families."

Rock musicians provide the most telling statistics. Sixty percent of the inductees into the Rock and Roll Hall of Fame are hearing-impaired, according to the Self Help for Hard of Hearing People Inc. Meanwhile, the musicians advocacy group Hearing Education and Awareness for Rockers (HEAR), says 86 percent of musicians and music fans hear ringing after a concert. It's no longer a badge of honor, according to HEAR national spokeswoman and rocker Pat Benatar, whose message to youth is: "It's Hip to H.E.A.R."

Reference Source 112
August 16, 2005

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