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People should listen to music for no more than one hour a day to protect their hearing, the World Health Organization suggests.

It says 1.1 billion teenagers and young adults are at risk of permanently damaging their hearing by listening to "too much, too loudly".

It said audio players, concerts and bars were posing a "serious threat".

WHO figures show 43 million people aged 12-35 have hearing loss and the prevalence is increasing.

In that age group, the WHO said, half of people in rich and middle-income countries were exposed to unsafe sound levels from personal audio devices.

Meanwhile 40% were exposed to damaging levels of sound from clubs and bars.

The proportion of US teenagers with hearing loss went from 3.5% in 1994 to 5.3% in 2006.

WHO v The Who

Dr Etienne Krug, the WHO's director for injury prevention, told the BBC: "What we're trying to do is raise awareness of an issue that is not talked about enough, but has the potential to do a lot of damage that can be easily prevented."

The full report argued: "While it is important to keep the volume down, limiting the use of personal audio devices to less than one hour a day would do much to reduce noise exposure."

Dr Krug said that a good ambition aim: "That's a rough recommendation, it is not by the minute, to give an idea to those spending 10 hours a day listening to an mp3-player.

"But even an hour can be too much if the volume is too loud."

Safe listening levels

Image copyright Thinkstock Image caption Keep that vuvuzela away from me

The louder the noise (measured in decibels), the faster it damages the ear.

The WHO's safe listening times are:

85 dB - the level of noise inside a car - eight hours

90 dB - lawn mower - two hours 30 minutes

95 dB - an average motorcycle - 47 minutes

100 dB - car horn or underground train - 15 minutes

105 dB - mp3 player at maximum volume - four minutes

115 dB - loud rock concert - 28 seconds

120 dB - vuvuzela or sirens - nine seconds

The World Health Organization recommends keeping the volume to 60% of the maximum as a good rule of thumb.

For people trying to drown out the noise of flying or train journeys, it says noise-cancelling headphones allow music to be heard clearly at a lower volume.

And the WHO adds that ear plugs should be worn at noisy venues and advises taking "listening breaks" and standing far away from speakers at gigs.

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But what is the point of a concert if you are going to avoid the music?

"We do realise this is a bit of a struggle, like alcohol consumption, so many risk factors linked to pleasure are not easy to change, but we have to make people aware," Dr Krug said.

But as well as calling for personal responsibility, the WHO says governments and manufacturers have a responsibility.

It says clubs should provide chill-out rooms and give out free ear plugs, headphone manufacturers should set limits on the volume, and governments need to adopt stricter laws.

Paul Breckell, the chief executive of the charity Action on Hearing Loss, said: 'When listening to loud music, for every three decibel increase in level, to stay safe you should halve your listening time.

"For example, at 88 dB, safe allowable exposure is cut to four hours, at 91 dB, two hours and so on.

"I urge music lovers to consider the long term risks of listening to loud music from their personal music players over the 85dB safe level, as over exposure can trigger tinnitus, and remember that a good pair of noise cancelling headphones can make all the difference."