Researchers at Purdue University in Indiana conducting random examinations of students have discovered a growing incidence of noise-induced hearing loss, and they believe the trend is due to the growing increase of headphone usage. Robert Novak, director of clinical education in audiology at Purdue, believes that the increase in hearing loss in younger people is due to the growing popularity of portable MP3 players, cell phones, and other items that attach directly to the ears. "It's a different level of use than we've seen in the past," says Novak. "It's becoming more of a full-day listening experience, as opposed to just when you're jogging." Novak says he has begun to see a regular influx of young people with "older ears on younger bodies."

To document the trend, Novak and his colleagues have begun to randomly examine students to assess their hearing. Their assessments have uncovered a disturbing prevalence of what is known as noise-induced hearing loss. A person with noise-induced hearing loss has lost the ability to hear higher frequencies, often resulting in mild ringing in the ears or difficulty hearing conversations in noisy situations. Hearing specialists and audiologists are also seeing more people in their 30s and 40s—people who were teenagers when the Walkman debuted—suffering from pronounced tinnitus or whooshing or buzzing in the ears. "It may be that we're seeing the tip of the iceberg now," says Dr. John Oghalai, director of The Hearing Center at Texas Children's Hospital in Houston, who's treating more of this age group. "I would not be surprised if we start to see even more of this."

Noise-induced hearing loss can occur from any number of situations, including using loud power tools, driving recreational vehicles such as motorcycles or snowmobiles, using firearms, or attending noisy concerts. One telltale sign that you may have done damage to your eardrums is when you leave a loud situation and feel your ears ringing. Often the ringing will subside and your ears will recover if you give them some rest. But repeated exposure brings with it the potential for more damage to the hair cells in the inner ear, which are vital to maintaining good hearing. And with today’s society becoming more and more addicted to constant use of headphones, not just to enjoy music, but also to block out annoying ambient noise on buses, subways, or outside the window, the problem will continue to get worse.

One stroll across a college campus will show how prevalent the trend is, with people carrying portable music players or cell phones, ear buds stuffed firmly in their ears, while working, studying, exercising, or reading. And thanks to rechargeable batteries that last forever, as well as iPod players that hold hundreds of songs, people who use portable music players are listening much longer than ever before, and not giving their ears a chance to rest and recuperate. Dr. Colin Driscoll, an otologist at Minnesota's Mayo Clinic, points out that many people don’t have any idea how risky headphones can be. "The tricky part is that you don't know early on. It takes multiple exposures and sometimes years to find out," Driscoll says. According to Deanna Meinke, an audiologist at the University of Northern Colorado who heads the National Hearing Conservation Association's task force on children and hearing, having sounds produced so close to the eardrum is already a hazard, but people also turn up the volume to ear-damaging levels. A survey by Australia's National Acoustic Laboratories found that about 25% of people using portable stereos had daily noise exposures high enough to cause hearing damage. Research by Britain's Royal National Institute for Deaf People determined that young people age 18 to 24 are more likely to exceed safe listening limits.

Using headphones needn’t be abolished altogether to protect your hearing. Researchers at Boston Children’s Hospital have determined that it is relatively safe to listen to a portable music player with headphones set to no higher than 60% of its potential volume for one hour a day—not for hours at a time. Experts also recommend protecting hearing in other ways, many of which have been recommended for decades, ever since the advent of rock and roll concerts. Standing away from loud speakers, using hearing protection while working with loud machinery, and carrying earplugs to wear in noisy situations can all help protect against unnecessary and potentially damaging noise. Of all the five senses each person has, hearing is the one most often taken for granted. But it’s also the one that’s easiest to protect.