It appears that all those ears ringing from newly gifted iPods and MP3 players may have a harder time hearing next year's Christmas bells if music lovers aren't careful, hearing specialists are warning.

"We're seeing the kind of hearing loss in younger people that's typically found in aging adults," said Dean Garstecki, an audiologist and professor at a UIS University. The big culprits aren't the devices themselves, but the tiny "ear bud" style headphones that the music players use. "Unfortunately, the ear buds are even more likely to cause hearing loss than the muff-type earphones that were used on Walkman and portable CD players," Garstecki said.

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In a study published last year in the University journal Ear and Hearing, researchers at Harvard Medical School looked at a variety of headphones and found that, on average, the smaller they were, the higher their output levels. Other studies have shown that because the tiny phones inserted into the ears are not as efficient at blocking outside sounds as the cushioned headsets, users tend to crank up the volume to compensate.

"With headphones, I tend to get carried away with the volume," said Dan Holmes, 23, of Antrim. Holmes and his twin brother, Tom, are always listening to music. Each has about 300 records, 500 CDs and enough MP3s to fill four or five iPods. They also produce "noise music," which usually involves jamming cacophonously on random instruments. Once, they recorded an hour-and-a-half of guitar and bass feedback, mixed with a reed organ.

At least, they say, they did it quietly. But Dr. Jeffrey Byer, an ear, nose and throat physician in Manchester, said many young people are overdosing on loud noises. Over the past 20 years, Byer said, he's seen a large spike in the number of young people complaining of ringing in their ears.

"You get the history of these kids: They have no infections, they're not taking toxic drugs." he said. "The only common experience is either they go to theaters, like the Verizon . . . or they wear these Walkman devices with these earphones and crank the noise up." At 24, Alexis McKenney is already noticing some hearing loss. She's been going to hardcore and metal concerts about twice a week for a decade now, and when she isn't hearing music live, she listens to it on her iPod with ear-bud headphones.

"My own hearing, as well as a lot of my friends', is pretty bad," said McKenney, the assistant manager at Newbury Comics in Manchester. "I'm sure I'm only making it worse with my iPod." Hearing advocates are pressing for people to turn down the volume. The rule of thumb suggested by researchers at Boston Children's Hospital is to hold the volume of a music player no higher than 60 percent of the maximum, and use it for only about an hour a day. The National Hearing Conservation Association also recommends that parents try to find audio gear for their kids that have volume-limiting devices built-in.

Meghan Crawford, a 16-year-old from Merrimack, said she used to wear ear buds all the time, but recently she switched to muffs. "I didn't like them," she said of her old set of ear buds. "They hurt my ears a lot." Of course, she might have saved some money and just lowered the volume. "I could've," she said. "But I liked it loud."