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The Sound of Silence
Portable music players and hearing loss

For the last few decades, it has been easy to carry our favourite music along with us. The current MP3 player is just the latest version of almost-forgotten portable devices like cassette and CD players. Newer players are smaller, cheaper and longer lasting, and can be filled with vast quantities of audio on demand. Ear bud-type headphones that sit in the ear canal allow us to tune in without disturbing those nearby. As a result, portable music players can used almost anywhere by people of all ages around the world. However, modern players can operate at very high volumes, posing a threat to hearing. Any noise has the potential to cause permanent hearing loss, if it is loud and listened to for long enough.

Loudness

Loudness (intensity) of noise is often measured in units called decibels (dB). Decibels measure the relative loudness of noise. An increase in ten dB of a sound indicates that a sound has become approximately ten times louder. An increase in twenty dB of a sound means the sound is 100 times louder. The loudness (dB) of some sounds found in day-to-day life is shown in Table 1. MP3 players can be extremely loud. Some produce the level of noise heard at rock concerts.

Exposure

Research from workplaces has shown that long-term exposure to loud noises can permanently damage hearing. Occupational health regulations often limit workers’ exposure to 80 dB for an eight hour period. A relationship exists between dB exposure and time. Workers can be exposed to noise in a louder environment, but for a shorter period of time . For instance, a worker might be exposed to 83 dB, but only for a four hour period. By listening to an MP3 player set at 95 dB, you will reach the maximum daily allowable noise exposure in only 15 minutes. The ear-bud type headphones used with MP3 players are another consideration. They sit in the ear canal and are designed to deliver high levels of sound in noisy environments.

Listening to high intensity noise for long periods of time can result in permanent hearing loss. It damages the cochlea (hearing organ) in the inner ear. The cochlea is made up of tiny hairs, each responding to sound (vibration). With frequent, loud noise exposure, these hair cells sustain damage and cannot recover. As hearing loss progresses, it becomes difficult to make out common speech patterns. Ultimately, the ability to identify environmental sounds may be lost.

Apart from permanent hearing loss, prolonged exposure can result in tinnitus (ringing in the ears), less ability to communicate and changes in behaviour. The effects may be seen at home, work and in social settings. In children, hearing loss can impact speech and language development, academic achievement and social development.

Who is at risk?

Well over 250 million MP3 players have been sold worldwide. Children, teens and adults use portable music players, and one out of every five people under the age of 30 may have an MP3 player. All are at risk of permanent hearing loss. By listening to a player at high volume more than an hour a day for five years, as many as 10 per cent of young users may suffer permanent hearing loss.

According to the Canadian Community Health Survey, about four per cent of Canadians have enough hearing loss to prevent them from communicating in a group of three or more without a hearing aid. One per cent of 11 to 20 year olds say they have a hearing problem. Almost everyone who listens to a MP3 player for long periods of time is at risk of permanent hearing loss.

What can I do?

Some companies have already capped the maximum volume that their devices are capable of producing. Often this self-imposed cap is in the 90 to 100 dB range, which could still cause damage. It is best to consciously set the volume level of your MP3 player below 60 to 70 per cent maximum. With many units, setting it any higher may result in sound intensity that, heard long enough, could cause irreversible damage.

You can also limit the amount of time you listen to MP3 players at high volume. Take frequent breaks to give your ears a chance to recover. Remember, damage occurs with high sound intensity for long periods of time. Normal hearing will return if you give your ears a chance to rest.

Headphones that block out background noise may help as well. Listeners often turn up the volume of portable devices to drown out noise around them. Instead, use headphones that block or remove unwanted environmental noise. You will need less volume to hear your music and can listen longer.

Suspect hearing loss?

• Do you have a hard time following conversation when there is a lot of background noise (at a party or in a cafeteria)?
• Does it often seem that those around you are mumbling?
• Do you hear a ringing, buzzing, roaring or rushing sound (tinnitus) when there is nothing to hear?
  These can all signal damage to your hearing.

While listening to music on the go may improve your lifestyle, permanent hearing damage will not. If you are concerned about possible hearing loss in yourself or your child, talk to your doctor about having a hearing test done.