One good way to visualize noise-induced hearing loss is to imagine walking back and forth across the same patch of grass every day, said Anne Oyler, audiologist at the American Speech-Language Hearing Association. If you keep on doing it, eventually you're going to wear down the grass. And if you continuously bombard the very delicate hair cells in the ear -- which move every time noise stimulates them -- eventually they'll wear down too.
Surprisingly, children are the fastest-growing population wearing down those cells. The National Institutes of Health report that 12 percent of children ages 6 to 19 have reduced hearing caused by excessive noise.
Perhaps not so surprisingly, the average amount of time an 8- to 18-year-old spends listening to music and other audio, such as the news or talk shows, is around 2 1/2 hours a day, up from 1 3/4 hours in 1999, according to a Kaiser Family Foundation Study released in January. On average, 30 percent of the music and audio children listen to comes from a portable audio device, such as an iPod or other MP3 player.
But just because more children have hearing loss and more of them are listening to music on such devices doesn't mean that the devices themselves are to blame for the situation, experts said. And while noise-induced hearing loss is cumulative and irreversible, it is also completely preventable, they added.
Hearing loss has little to do with the source of the sound and everything to do with the dosage, or the level of the sound and the amount of time spent listening to it, said Catherine Palmer, audiologist and director of UPMC's Center for Audiology and Hearing Aids.
MP3 players don't cause hearing loss, and it's not any more dangerous to listen to music from an iPod than it is to listen to music from a stereo or car speakers, experts said.
"Sound is sound. The ear doesn't care how it got there," Dr. Palmer explained.
The problem with MP3 players comes when people listen to them for too long at levels that are too high.
The greater the exposure, the greater the chance of hearing loss because it builds up over time, Dr. Palmer said.
Both experts cited educational programs as ways to help prevent hearing loss.
The Listen to Your Buds campaign, sponsored by the American Speech-Language Hearing Association, raises awareness about hearing health and educates children about good habits, such as turning down the volume and taking "listening breaks," Dr. Oyler said. UPMC runs a program through its Musicians' Hearing Center to educate music instructors about the dangers of loud sounds and to equip instructors and students with appropriate musician earplugs.
"Hearing protection in orchestra and band in the schools is no different from having children wear safety goggles in chemistry or football helmets on the football field. It is a way to make the activity safe," Dr. Palmer said in an e-mail.
Remy Porter, 30, of Shadyside, who works as a programmer for PPG Industries, does monitor his listening habits. He said that when he was in a band, he was the "only member who actually went out of [his] way to wear earplugs."
Besides using hearing protection, people can protect their ears by listening to music on their iPods at reasonable levels.
Normal conversation levels are around 50 to 60 decibels, but iPods at full blast can reach around 105 or 110 decibels. Research shows that extended listening to sounds that are 85 decibels and up can be damaging.
Audiologist Brian Fligor of Boston Children's Hospital reported data that indicated an 80-90 rule, meaning that individuals should listen at 80 percent of their volume wheel setting for no more than 90 minutes per day, Dr. Palmer said.
Taylor Stevenson, 8, of Crafton Heights, listens to his iPod around an hour a day, often with the volume turned all the way up. His mother, Colleen Stevenson, 34, said that while she sometimes monitors his listening habits, she'd rather he listen to music than watch television.
A good rule of thumb is that if a parent can hear a child's music outside while the child is wearing a headset, it's too loud, said Dr. Oyler. But if background noise or noise-isolating ear phones are involved, that rule no longer applies, so Dr. Oyler suggests setting a comfortable level in a quiet location and then noting where the volume is set.
Cindy Pastin, 48, of Robinson, said she only listens to music at about a quarter of the volume wheel when she's inside. But when she goes outside for her walk, lasting around 35 minutes to one hour, she turns the volume to full blast.
To block outside sounds, custom earbuds can be made to perfectly fit your ear. Such earbuds make it possible to listen to music at a quieter, and healthier, level, Dr. Palmer said.
Ms. Pastin said custom earbuds are not something she had ever considered. Bojan Popovic, 26, of Aliquippa -- who listens to music between six and eight hours a day when he's studying -- had never heard of the custom earbuds. But Mr. Popovic has been considering purchasing earbuds that block outside sound, and so he said might look into the custom buds too.
Drawbacks include the trip to the audiologist, the $50 price tag and safety issues associated with not being able to hear outside noises.
Speech sounding less clear, ringing, buzzing, or a fullness sensation in the ear are all signs to go in for a hearing evaluation, experts said.
Luke Debranski, 28, of South Park, tries to keep his volume levels at a minimum because he has ringing in his ears at times. He usually listens to music at around three quarters of the wheel for approximately two hours each week, and he gets his hearing checked about once a year.
UPMC has a free screening number that individuals can call to have an automatic hearing screening over the phone. That number is 412-647-2400.
Katie Falloon: firstname.lastname@example.org or 412-263-1723.