Personal Listening Devices and Hearing Loss

Published May 12, 2009
By Capt April Taylor, Audiologist
48th Medical Group

ROYAL AIR FORCE LAKENHEATH, England --

Life can be very loud! Studies have shown that over the last several years environmental noise has doubled each decade. It seems that volumes are cranked up everywhere: movies, iPods/MP3s, power tools, and rock concerts. The National Institute on Deafness reports that at least 30 million Americans have hearing loss, and that number is quickly increasing. Noise-induced hearing loss is a huge concern and is on the rise even among very young people.

Now, I love my iPod as much as the next person. However, we need to be responsible when it comes to taking care of ourselves, and this includes our hearing. I want to share some facts about personal listening devices, their potential to damage our hearing, and what we can do to continue to safely enjoy our iPods and MP3 players.

You've seen people everywhere listening to their iPods or MP3 players. Often you can hear what they're listening to because they have the volume turned up so high. If you can hear someone else's music from about three feet away, then it is very likely that they are giving themselves hearing loss. A study by the National Foundation for the Deaf released in September 2008 noted seven out of 10 people under the age of 30 have signs of permanent hearing loss after listening to loud music. Hearing loss due to personal listening devices is totally preventable.

How loud can we safely turn up our headphones when we listen to music? It is recommended that iPod and MP3 users set the volume no higher than 60 percent of their full capacity when using ear-bud style headphones, like those that come with iPods. With over-the-ear headphones, 70 percent is recommended as the maximum. The closer to the eardrum the sound is, the greater the risk of damage because the sound levels are higher closest to the eardrum. "Insert earphones can boost the signal by as much as six to nine decibels, the unit which is used to measure the intensity of sound. That's about the difference between the sound of a vacuum cleaner and a motorcycle," according to Dean Garstecki, a professor at Northwestern University.

To reduce the risk of hearing loss, many experts suggest keeping your iPod or other personal music player set at no more than 60 percent of the peak volume and listening for no longer than 60 minutes a day. You can probably listen safely for longer if you're willing to turn the sound down even lower. For ear buds or other in-the-ear headphones, it is half that amount of time, around 30 minutes, at which point you are already at your safe daily dose. How many of us know people who wear them for several hours a day with the volume cranked up? Most research in noise-induced hearing loss has focused on sound exposure in the workplace, and the National Institute for Occupational Safety and Health has set the safe limit for noise exposure at 85 dB for eight hours a day. Each time the noise level increases by three dB, safe exposure time is cut in half, according to NIOSH.

Our ears can become desensitized to loud sounds, so it is very important that we pay close attention to the dial and not rely on how loud it actually sounds. Sometimes people turn up the volume of their iPods to overcome the level of background noise, not realizing the potential damage they're doing to their hearing. By limiting the amount of background noise, by using noise-cancelling headphones for example, you can still enjoy listening while keeping the volume down. iPods and Sony Walkmans with ear buds can go as high as 130 decibels, which is about the level of a jackhammer. Noise levels need to reach 120 dB to 140 dB to become uncomfortable or painful. iPods can generate sound volume at a level of 100 to 130dB. Compare this to the front row of a rock concert which is about 110-140dB or a military jet taking off which is about 160dB. Currently, Europe has already adopted volume caps on iPods at 100dB. However, there are no standards in the United States.

The longer we listen to loud noise, our auditory systems become more fatigued. This results in what is known as a temporary threshold shift. This condition can be accompanied by a full feeling in the ears, muffled hearing and ringing in the ears, also known as tinnitus. Repeated episodes of threshold shifts or even a single incident of intensely loud noise exposure can result in a permanent hearing loss and/or permanent tinnitus. A structure in the inner ear, called the cochlea, is lined with microscopic hair cells. These hair cells respond to auditory signals and work with the brain to create a perception of sound. The hair cells are easily damaged by excess noise and do not regenerate once they are gone. Often, noise-induced hearing loss occurs so slowly over time that we don't even realize damage is occurring until it is too late.

University of Florida research shows that 17 percent of middle- and high-school students already have lost some ability to hear. Reportedly, the problem will keep getting worse if they don't protect themselves from dangerous exposures to loud music, motorcycles, target-shooting and other noise hazards. It is strongly recommended that parents inform their children and discuss with them the use of personal listening devices and the potential long- term, irreversible effects they can have on their hearing. There are general signs that parents or family members can look for, such as complaints of tinnitus, sounds being muffled, and increased difficulty understanding speech. People exposed to volumes of 85dB or greater for eight hours usually tend to develop hearing loss. Children, who may not appreciate the many problems hearing loss can cause later in life, are especially vulnerable to noise-induced hearing loss. iPod users may consider downloading Apple's free software update that allows users to set maximum volume limits on the player. Using a combination code, this update lets users and parents set and lock in volume caps. The free download is available for the iPod nano and fifth-generation iPod.

Current estimates indicate noise-induced hearing loss affects from 10 to 15 million people in the United States. Stated simply, as many as one in 10 users of personal listening devices are at risk to suffer permanent hearing loss if they listen to a device at high levels more than one hour a day for five years. Bottom line: iPods and MP3 players are great, but we need to use common sense and protect our hearing. It is encouraged that if you want to listen to your iPod all day, you should limit the volume. If you want the volume louder, you need to limit your listening time. Be smart about noise exposure and wear hearing protection when necessary because once your hearing is gone, it's gone. Even with hearing aids or other amplification devices, life won't sound nearly as good as with your natural hearing.

Editorial Note: For over 75 years, May has been designated as Better Hearing and Speech Month. The month of May is used to raise public awareness, knowledge, and understanding of the various forms of communication impairments to include those of hearing, speech, language, and voice.

For more information or assistance with hearing or speech issues, please contact the 48th Medical Group's appointment line at 314-226-8010.