Be careful of the volume on iPod earbuds

Earbuds are not more dangerous than traditional headphones, but teenagers are notorious for turning the volume way up.

The couple was new to my practice, having recently moved to the area from another state. Their son was in the office for a physical before starting classes and sports at his new junior high. I had already reviewed the healthy teen's medical history and was starting the exam when the boy casually mentioned that he had failed a screening test within the past year.

Yes, the aspiring musician admitted, he had not passed the state-mandated hearing test at his old school. I asked him what advice he'd been given after the testing, and he simply stated, "They told me not to listen to my music so loud."

The American Academy of Otolaryngology notes that noise damage is the most common cause of hearing loss in the United States. Noise-induced hearing loss is not a new medical phenomenon, but while occupational exposure used to account for most of these cases of sensorineural hearing loss, recent decades have seen an upswing in recreational hearing damage.

The rising popularity of smaller, more portable music devices and more form-fitting earbuds has added a new wrinkle to an old problem. Though many teens think they can build tolerance to loud music over time, experts assure us that this is not the case. Once it occurs, noise-induced nerve damage can never be fully reversed, despite the best efforts of modern medicine.

Otolaryngologists explain that the intensity of sound is measured in decibels, with 0 decibels equaling the faintest sound able to be detected by the human ear and 60 decibels representing normal levels of conversation. Prolonged or repetitive exposure to 85 decibels or greater can cause permanent hearing loss.

Loud rock concerts can reach noise levels of 115 decibels. If your teen was out in the workforce, by law, his unprotected ears could be exposed to that same 115 decibels of sound for no more than 15 minutes per day.

Though rock concerts are an infrequent source of noise exposure for many kids, what about their personal music systems? An eye-opening study conducted in 2006 by the American Speech-Language-Hearing Association found that nine popular handheld sound devices reached maximum decibel levels of 106 to 125 when played at full volume.

Is there an acceptable volume level for these music devices? In papers presented at a recent NIHL in Children Meeting, researchers from Harvard and the University of Colorado used occupational noise standards to develop their own recommendations for iPod earbud use.

The authors suggest restricting listening time based on selected volume. If the device is kept at 10 percent to 50 percent of its maximum volume, no limit needs to be put on its use. If, however, the owner chooses to listen at 80 percent volume, suggested listening time drops to 90 minutes per day. At maximum volume, no more than five minutes of listening time should be allowed in a day.

The same researchers found that the much-maligned earbuds are not more dangerous than over-the-ear headphones. Earbud users, however, are notorious for turning the volume way up when they find themselves unable to hear their music due to loud background noise.

Volume guidelines can be helpful, but parents will find that each child has his or her own individual noise limit. Some kids (and adults) really are more sensitive to noise and will need to drop the volume level even lower than the accepted safe levels.