Justin Roberts has wildly curious young fans, the type who might lean into a live monitor during one of his concerts just to see what it sounds like.

But the popular children's entertainer knows a blast of loud music isn't the only risk to a child's hearing. What parents and kids really need to watch is the everyday use of earbuds that come with iPods and other MP3 players, said Roberts, who has teamed up with the American Speech-Language-Hearing Association to raise awareness about noise-induced hearing loss.

Not only do earbuds send sound directly into the delicate ear canal, but they boost the volume by as much as 9 decibels. And because today's devices can hold and play music for longer periods, kids are wearing them more than the recommended one hour a day, putting them at risk for permanent hearing loss after just five years, according to the ASHA.

"Sound can be dangerous as well as fun," said Roberts, who headlined a "Listen to Your Buds" concert for school groups recently at Chicago's Museum of Science and Industry. "It's an important message to get out to kids when they're young and their hearing is still great."

Studies show hearing loss is already affecting a younger population. More than half of high school students in the U.S. report having at least one symptom of hearing loss, according to a 2006 poll commissioned by ASHA. Another survey showed that 5.2 million 6- to 19-year-olds have some degree of hearing loss directly related to noise exposure.

The damage is based on two variables: the decibel level and duration of exposure.

Conversation measures 60 decibels on a sound meter. At 70 percent volume, an MP3 player can pump out 85 decibels, the recommended safe listening level.

But the gadgets are often played at 100 or even 120 decibels — the equivalent of a gunshot or a jet engine — which is enough to cause permanent damage.

The inner ear contains about 30,000 hair cells, which are tuned to specific frequencies, said audiologist Dennis Burrows, vice president for standards and ethics in audiology for ASHA. Loud music can destroy these cells; the first ones to go are the ones responsible for the highest frequencies.

"Prolonged and loud exposure, much like lots of foot traffic through a doorway wears down carpet, will shear off these hair cells," said Burrows.

Roberts, who said The Who concerts taught him that "loud rock music was the coolest thing in the world," now takes precautions to protect his own hearing — especially since musicians Roger Daltry and Pete Townshend of The Who suffer from hearing loss. He also tries to keep his own concerts at safe levels.

But he also acknowledges that he's part of a rock band; the audience also should play it safe.

"Use ear protective devices for kids who are more sensitive or be aware that kids might be up front and dancing," said Roberts. "Whether it's leaning into a live monitor or using earbuds, kids are going to be exploring the world."