Toronto, April 7 (IANS): Loud music from smartphones can cause permanent hearing loss, researchers warn. The World Health Organisation (WHO) has said in a recent report that over a billion young people are at risk of permanent hearing loss.

Shelly Chadha, prevention of deafness and hearing loss technical officer for WHO, said the danger with smartphones is that many people are listening to music that is simply too loud.

"Anything where you're putting sound into the eardrum, that's something as a society that we need to take a closer look at," Rex Banks, chief audiologist at the Canadian Hearing Society, was quoted as saying by CBC.ca.

That's because loud noises damage the cilia of the inner ear, the tiny hair-like structures that change sound waves into electrical signals that are carried to the brain. The damaged cilia never grow back.

"Once they've been damaged, that's irreversible," Banks said.

Compounding the problem is the fact that people often listen to music when they are out on the street or in the subway where there is a lot of other background noise.

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

A normal speaking voice usually measures around 60 decibels. Volumes above 85 decibels will cause damage after about eight hours and levels above 100 decibels can do so in 15 minutes.

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