It's easy to get caught up in a good song, but cranking up the stereo or iPod to excessive levels on a regular basis can leave you saying, "Whadya say?" before your time.

Young people who blast their music, whether in the car or while listening to an MP3 player, will "have a head start on being old. That's for sure," says Ian Windmill, director of audiology at the University of Louisville in Kentucky. "We're seeing the same kind of hearing loss in teenagers that we see in people that are over 60 years of age."

Car stereos can reach 120 decibels, louder than a chain saw and pretty close to a jackhammer, according to the American Speech-Language-Hearing Association.

An estimated 5.2 million U.S. children, ages 6 to 19, have a hearing loss in one or both ears because of noise, according to a study published in the journal Pediatrics in 2001.

"The louder the sound one is exposed to, the more risk one has for sustaining hearing loss," Windmill says. "In the United States, the most common cause of hearing loss is noise exposure."

And repeated exposure usually gets people into trouble.

Prolonged exposure to noise can damage tiny hair cells in the inner ear that play a key role in how we hear, says Dr. Ravi N. Samy, a specialist in ear diseases at the University of Cincinnati Academic Health Center and Cincinnati Children's Hospital Medical Center.

"More noise over time has a cumulative effect on the hair cells," which can die out, and "we don't have any techniques to get those hair cells to grow back," Samy says.

Hearing aids can help people suffering from hearing loss, says Jill Preminger, an associate professor of audiology at U of L. "But they don't give you back your normal hearing, and it's so frustrating for us to see a preventable hearing loss happening," she says, adding that hearing loss can negatively affect school performance.

Signs that you've been exposed to noise that was too loud include ringing in the ears and "temporary threshold shifts" in which it's difficult to hear for a while, Ashley says.

"Have you ever been to a concert where you come out and feel like your hearing is dulled for a while?" Windmill says. "That's a temporary threshold shift," so you've fatigued your ears. "You do that a few too many times, and ... you're going to end up with a permanent loss."

There's also a road-safety issue to keep in mind, says Louisville audiologist Laura Hogan, president of the Kentucky Speech-Language-Hearing Association.

Drivers with the "woofer things in the trunk, literally, I don't know how they'd hear a car coming up behind them," Hogan says. "I, personally, feel very unsafe next to somebody like that."