CHICAGO -- Everywhere she turns, Angella Day sees people carrying portable music players, often with the ear buds stuffed firmly in place. ''They're very widespread," says Day, a senior at Chicago's DePaul University who regularly listens to music on her own iPod while studying or working out. ''So addicting."
What she and others may not realize is that many people their age have already damaged their hearing. And researchers fear that the growing popularity of portable music players and other items that attach directly to the ears -- including cellphones -- is only making it worse.
''It's a different level of use than we've seen in the past," says Robert Novak, director of clinical education in audiology at Purdue University in Indiana. ''It's becoming more of a full-day listening experience, as opposed to just when you're jogging."
Increasingly, Novak says he's seeing too many young people with ''older ears on younger bodies" -- a trend that's been building since the portable Walkman made its debut a few decades back.
To document the trend, he and colleagues have been randomly examining students and found a disturbing and growing incidence of what is known as noise-induced hearing loss. Usually, it means they've lost the ability to hear higher frequencies, evidenced at times by mild ear-ringing or trouble following conversations in noisy situations.
Hearing specialists say they're also seeing more people in their 30s and 40s -- many of them among the first Walkman users -- who suffer from more pronounced tinnitus, an internal ringing or even the sound of 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 happens any number of ways, from attending noisy concerts and clubs to using firearms or loud power tools or even recreational vehicles. Snowmobiles and some motorcycles are among the offenders.
Today, doctors say many people also are wearing headphones, not just to enjoy music, but also to block out ambient noise on buses, trains, or just the street. And all of it can contribute to hearing loss.
''The tricky part is that you don't know early on. It takes multiple exposures and sometimes years to find out," says Dr. Colin Driscoll, an otologist at Minnesota's Mayo Clinic.
One telltale sign that you've done damage to your ears is when you leave a loud venue with ringing ears. If you rest your ears, they might recover, at least partially, doctors say. But with repeated exposure comes more damage to the hair cells in the inner ear, which are key to good hearing.
With long-lasting rechargeable batteries, people who use portable music players also are listening longer -- and not giving their ears a rest, says Deanna Meinke, an audiologist at the University of Northern Colorado who heads the National Hearing Conservation Association's task force on children and hearing.
Often, she says, people also turn up the volume to ear-damaging levels.
A survey published this summer by Australia's National Acoustic Laboratories found, for instance, that about 25 percent of people using portable stereos had daily noise exposures high enough to cause hearing damage. And further research by Britain's Royal National Institute for Deaf People determined that young people, ages 18 to 24, were more likely than other adults to exceed safe listening limits.
How much is too much?
Meinke says a good rule of thumb comes from a study published in December: Researchers at Boston Children's Hospital determined that listening to a portable music player with headphones at 60 percent of its potential volume for one hour a day is relatively safe.