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Hearing loss from loud noise or music is permanent, but preventable. In the audiology clinic at Children's Hospital Boston, concerned parents often ask how they can keep their child from ending up with a hearing loss. When someone asks "How loud is too loud?" our challenge is to provide clear and understandable guidelines that will help people protect their hearing health.
My interest in the use of personal stereo systems and hearing loss prevention started while I was in graduate school. While doing a student rotation in a clinic one day, I tested the hearing of a fifteen-year-old boy who had a subtle permanent hearing loss. The pattern of the test results were very suspect as being from long-term noise, such as might be seen in someone who just started working in a noisy factory and wasn't using hearing protection. When we asked about different things in his life that were noisy, he pulled out a CD player with headphones and said he listened to his music a lot. When we asked him for the volume level of his earphones, he said, "All the way up! That's where it sounds best." When he asked how loud he could listen and not do more damage, we weren't sure how to best guide him.
We began to look at the issue closer to see if we could make recommendations on volume settings for safe listening with earphones. We measured the sound levels produced by many different CD players and headphones on the market. As expected, we found differences between the CD players as well as the different earphones. Generally, we found that listening to the device at a volume setting of "6" (where "10" is all the way up) would be OK for one hour per day or less. Because some of the smaller in-the-ear earphones boosted the levels higher at level "6" than the over-the-ear headphones, the highest volume setting that would be OK for listening for an hour was lower. Our findings were published in the December 2004 "Ear and Hearing" Journal.
Now, with MP3 players (like the Apple iPod), people can listen for longer periods of time more easily than CD players. Since risk for hearing loss is from not just how loud, but also how long you listen, basing a guideline on one hour of listening doesn't make sense. Duration of use is something to consider when thinking about "hearing loss risk."
Knowing what levels music players can produce is interesting. It might help us to set safe-listening guidelines, but we still need to know how people use the devices. When most people listen to their earphones, they're not listening at the maximum level. Some like music louder, some like it softer. When you like a song, you might turn the volume up, but then when the song's over, you might turn it back down again. If you are listening at home in quiet, you might listen at a moderate level. But if you fly on an airplane, where the sound around you is very loud already, you might turn up the volume.
To get a better understanding of why people listen to loud music, and what we might do to help a person listen at safer levels, a colleague, Dr. Terri Ives, at the Pennsylvania College of Optometry, School of Audiology, and I are conducting a study. We are examining how many people listen loudly no matter what, and what happens when moderate listeners try to listen to music when it's noisy around them.
So far we've found that when it's very quiet, the majority of people listen at safe levels. But even in the quietest room, some people (between 5 and 25% of them) set their music to high levels that might be risky if they listened for too long. People who were more moderate listeners do turn their music up, though, when the background noise around them starts to get loud. For example, when we ask people to set their music to the level they like, and we make the room as noisy as flying in a typical passenger airplane, they often set the music to a level that would be problematic for more than a couple hours. An easy solution would be to use an earphone that is designed to block out background noise. Our study's sponsor, Etymotic Research, Inc., is one of a few manufacturers that makes earphones that are designed to block out background noise. People who use this type of earphone tend to set their music to more moderate levels. However, when environmental noise can be heard-such as when riding in an airplane, subway, or on a bus-people generally turn up the volume.
Dr. Ives and I will be looking at just how many people are loud-music listeners, and see what we can do to help them to listen at safer levels, such as through directed education. We would also like to see what happens with people who already have hearing loss in one or both ears, since they may be listening louder to overcome their decreased hearing, even though doing so might put them at risk for even greater hearing loss.
Market reports have noted that one MP3 player has sold a total of 40 million systems since 2001. If only 5% actually listen to loud music regularly, and only a tenth of those people do this for years, as many as 200,000 people could have hearing loss from choosing to listen too loud for too long. This hearing loss from listening to music too loudly is permanent, but entirely preventable. We hope that current research and education efforts protect the hearing of as many people as possible.
Return to Brian J. Fligor's Biography
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