More research is needed to determine whether popular portable music players like Apple’s iPod increase the risk of hearing loss, the National Institutes of Health said in response to a lawmaker’s request for a review of the issue.
A recent survey commissioned the American Speech-Language-Hearing Association suggested that U.S. teenagers are listening to iPods and other MP3 players too loud and too long. And more than half of high-school students reported at least one symptom of hearing loss.
Earbud headphones, like the ones typically used with iPods, project sound directly into the ear canal, while traditional earmuff-style headphones allow the sound to diffuse, the NIH said in a Feb. 14 letter made available Tuesday.
The proximity of the source of the sound to the ears can contribute to hearing loss, but “more research is required to determine if a particular type (of earphone) increases the risk,” said James Battey, director of the National Institute on Deafness and Other Communication Disorders, in the NIH letter.
Rep. Edward Markey, a Massachusetts Democrat, sent a letter earlier this year asking NIH to review research to determine whether portable music players are contributing to premature hearing loss as well as to recommend what people can do to prevent it from happening.
Markey said at a panel discussion Tuesday that he plans to work with Rep. Mike Ferguson, a New Jersey Republican, to encourage more study of a possible connection.
“Sales of the devices have shattered all expectations,” Markey said. “There is a very real need for research.”
Ferguson said he is concerned about the potential risk because many portable music device listeners are children.
“Kids are often more familiar with these products than parents, but they don’t realize how harmful these products can be to hearing,” he said. “It can lead to a lifelong ailment.”
Apple, which dominates the market for the devices, alone sold 14 million iPods during the Christmas holiday quarter and said in January that it had sold 42 million devices since October 2001, when the iPod was introduced.
A spokeswoman from Apple was not immediately available for comment.
Sony Corp. and Thomson’s RCA also sell portable music players, and Cingular Wireless, the largest U.S. wireless carrier, offers Apple’s music software in a cell phone.
Research into the phenomenon began in the early 1980s, soon after the 1979 introduction of portable radio and cassette players with headphones, like Sony Corp.’s Walkman.
The NIDCD during a 1990 conference concluded that “sounds of sufficient intensity and duration could damage the ear and result in temporary or permanent hearing loss at any age,” Battey said.
He said research on the subject has surged in the past few years, following the introduction of portable MP3 players, which have maximum sound output levels comparable to the sound level of a jet engine.
Although recent studies have concluded that users should hold the volume of a music player to no higher than 60 percent of the maximum, Markey said more research is needed to help consumers.
“It is critically important to work to determine the best ways consumers can protect themselves from noise-induced hearing loss,” he said.