Smartphones can blast your hearing, health report warns

Generation after generation, teenagers have been told by their forebears to turndown that music. Now there seems to be a good medical reason to do so.

The World Health Organization warned in a recentreport that over abillion young people are at risk for permanent hearing loss. One of the mainculprits is a widely used device for listening to musicthesmartphone.

"Anything where you're putting sound into the eardrum, that's something as a societythat we need to take a closer look at," says Rex Banks, chief audiologist at theCanadian Hearing Society.

That's because loud noises damage the cilia of the inner ear, the tiny hair-likestructures that change sound waves into electrical signals that are carried tothe brain. The damaged cilia never grow back. "Once they've been damaged,that's irreversible," says Banks.

Dr. Shelly Chadha, prevention of deafness and hearing loss technical officer forthe World Health Organization, explains the danger with smartphones is thatmany people are listening to musicthat is simply too loud.

Compounding the problem, says Banks, is the fact that people often listen tomusic when they are out on the street or in the subway where there is a lot ofother background noise.

Most earphones that come with smartphones and MP3 players do a poor job ofblocking ambient street noise. So in noisy urban environments, users frequentlyturn up the volume to maximum in order to overcome the din of city life.

He points out that most of us are slowly damaging our hearing without realizingit.

But the ears have their own way of signalling danger. Coming out of a nightcluband finding that your ears are ringing or that you have to speak loudly to hear yourown voice is a common situation that most people think is benign. But it isactually a defence mechanism your ears use to protect themselves fromdamaging noise levels, a phenomenon called a "temporary threshold shift."

Give your ears a rest

Banks says that when this happens you should get away from the noise giveyour ears a rest for about 12 hours. Hopefully, the damage hasn't becomepermanent and your hearing will recover.

There are ways to preserve your hearing.

A normal speaking voice usuallymeasures around 60 decibels. Volumes above 85 decibels will cause damageafter about eighthours and levels above 100 decibels can do so in 15 minutes. Butmeasuring decibel levels is impractical and complicated for most people.

Chadha recommends an easier test.

Sit in a quiet room and listen to your music at about 50 to 60 per cent of themaximum sound level of the device. You should still beable to carry on a conversation with a person sitting near you. If you can't hearthatperson,the music is too loud.

Banks recommends holding your ear budsand closingyour fistaround them. If you can hear the music through your fist, you're playing ittoo loud.

Some solutions

One solution to the problem could be noise-cancelling earphones that can blockambient sound and allow music lovers to listen to their music at lower andsafer volumes.

There are also built-in safety options for most devices. Apple introduced a way oflimiting the volume on its iPod and iPhone devices after a 2006 class actionlawsuit accused it of not taking adequate measures to protectits customers' hearing. Google has introduced similar volume-limiting apps for its Android devices.

But Banks warns that none of these features is perfect and nothingshould give you licence to expose yourself to as much noise as youwant.

He says the best strategy is to remove, reduce and rest: Remove yourself from prolonged loud sounds, reduce the amount of background noise around you and give your ears a chance to rest and recover.

Chadha says the goal of the WHOreport was not to scare people from using smartphones. She says that if you listen to your music at safevolumes, you can listen for long periods.

"We're not telling people not to listen to music, just to make sure that they listensafely forever."

Christopher Labos is a cardiologist and epidemiologist at the McGill University Health Centre. He is currently a fellow in global journalism at the Munk School of Global Affairs at the University of Toronto.