Turn it down - you hear?

Fu Hin-ngai, a Year 12 student at Sha Tin College, spends, on average, three hours a day listening to music, particularly when he's getting around town.

'I usually turn up my music when I go to busy, noisy places,' he says.

Hin-ngai is not alone. Take a trip on the city's MTR - or the trams or the buses - and you will see rows of commuters plugged into their iPods and other music players. Probably most of them, like Fu, crank up the volume in attempt to drown out the ambient noise. But, experts point out, these rows of commuters could be doing permanent damage to their hearing.

According to audiologist June H.C. Fok, doctors who specialise in hearing are seeing an increasing trend of young people for consultations, usually with tinnitus - or ringing in the ears. In the past, tinnitus was associated with older people who worked in noisy environments. But young people with the condition generally have another explanation for their hearing loss - listening to music.

The biggest problem, she explains, is that when people listen to music in an outdoor setting - particularly in a noisy city like Hong Kong, where the hum of traffic and roar of construction constantly assault the ears - they turn up the volume. She says they are effectively 'masking' the ambient noise of whatever environment they happen to be in. The risk is they may be increasing the volume of the music to such dangerous levels it damages their hearing.

The dangers are not only environmental. Janice Yan Tung, a 19-year-old Hong Kong student at the University of Toronto says the volume she listens to music at depends on her mood and the kind of music she is listening to. She says she turns up the music when she is feeling 'bubbly or upbeat' and when she is working out.

'I know it's too loud when my ears feel uncomfortable and, when I take off the earphones, all the sounds are muffled,' she says.

But reactions like this, says Fok, are precisely the warning signs young people should be aware of if they do not want to damage their hearing. She suggests looking for MP3 players with volume limiters. Apple's iPod, for example, has had a volume limit function since 2006. It was introduced after the company was threatened by legal action from users who alleged they were suffering hearing loss in the United States. Inevitably, programmers have responded by developing hack solutions to the volume limiter, but hearing specialists advise that it is dangerous to use them.

Late last year, the European Union proposed mandatory volume limits for all MP3 devices. EU experts recommend volume levels no higher than 80 decibels and for no longer than 40 hours a week.

Most iPods have a maximum volume of 100 decibels, which is the same as a standing next to a pneumatic drill.

Fok suggests investing in noise-isolating earphones which block out background noise.

'Earphones that block out sound make it less likely that you will turn up the volume to dangerous levels in noisy places,' she says.

But, she admits, ultimately it is the listener who determines the volume at which they listen to music. Hin-ngai says he uses noise-isolating earphones but sometimes needs to turn up the volume because the background noise is not completely blocked out.

Fok suggests following the '60/60 rule' - 'if you listen to your music device at 60 per cent maximum volume for less than 60 minutes a day, you should be safe from hearing loss,' she says.