Quotes of the Day

If you're one of the 173 million iPod users out there, you're probably reading this with your earbuds in.

Take them out. Even if only for a few minutes while you read this article.

Trust us, your hearing will thank you for it. While many music lovers are aware that listening to iPods and MP3 players at high volumes can lead to hearing loss, not many of them — especially not teens — do anything about it. In fact, when teens are pressured by friends or family to turn down the volume on their iPods, they do exactly what you'd expect them to do: they turn the volume up instead. Even teens who express concern about the risk of hearing loss listen to music at potentially dangerous levels — higher on average than kids who say they're not worried about deafness. (See the top 10 iPhone applications.)

Go figure. But that's what researchers at Colorado University and Children's Hospital in Boston found in a small study of 30 young iPod users. Led by Cory Portnuff, an audiologist at Colorado who began studying iPod-related hearing loss in 2006, the study found that teens not only tend to play music louder than adults, but they are often unaware of how loud they're playing it. "I honestly don't believe that most people understand they are putting themselves at risk, or at what level of risk," says Portnuff. (See pictures of a diverse group of American teens.)

Portnuff has documented that listening to earbuds, or in-ear headphones, for 90 minutes a day at 80% volume is probably safe for long-term hearing — a useful cutoff point to keep in mind. (But softer is better: you can safely tune in at 70% volume for about 4½ hours a day.) The risk of permanent hearing loss, Portnuff says, can increase with just five minutes of exposure a day to music at full volume. Over time, the noise can damage the delicate hair cells in the inner ear that transform sound waves to the electrical signals that the brain understands as sound.

So why would anyone ever listen to an iPod at maximum volume? Again, it's a simple misunderstanding of risk. Portnuff speculates that teens who say they worry about hearing loss but still listen to their iPods at high volumes probably assume that the manufacturer's maximum default setting is safe, or that turning the volume down to anything but full-blast is harmless. (Read "The Year in Medicine 2008: From A to Z.")

Add to these misconceptions the fact that people are listening to music for longer periods of time — today's long-lasting batteries can crank out music for 15 hours or more — and it's no wonder that the risk of hearing loss is increasing. But perhaps so is the concern. In 2006 a Louisiana man filed suit against Apple, claiming that iPods are "not sufficiently adorned with adequate warnings regarding the likelihood of hearing loss." Soon after, health authorities in France demanded increased safety measures. So the company, based in Cupertino, Calif., revised its software to set the maximum volume at 100 dB (the equivalent of standing next to a pneumatic drill) for devices sold in Europe. Portnuff says certain devices sold in the U.S. can reach beyond 100 dB, however; some have recorded levels as high as 115 dB, similiar to a chainsaw or rock concert.

Portnuff acknowledges that most iPod and MP3 users don't keep their devices at maximum volume — only about 7% to 24% listen at risky levels. But because most of us can, and are, spending more time listening to music through headphones, there is a real risk of hearing loss for anyone who plugs in. "It's a matter of how high you listen and for how long," he says. Listen for too high and too long, and you may have to replace those headphones with hearing aids in the not-too-distant future.

See pictures of the Rock and Roll Hall of Fame's 2009 nominees.

See 25 must-have travel gadgets.

• Alice Park