Hearing specialists are considering holding a study to find out if prolonged high-volume use of an MP3 player can affect hearing.
The move follows a surge in iPod sales and an Australian report revealing an increased incidence of tinnitus - ringing in the ears - among young people.
Medical experts in Hong Kong sounded the warning as more and more people get plugged in and pump up the volume of their players to block out city noise. The Australian government study said close to a quarter of users in that country were damaging their ears by turning up the music to 'excessive and damaging' levels.
Clinical audiologist for the OTIC Speech and Hearing Centre Loretta Li Yuet-wing said: 'If you are sitting on the MTR listening to your MP3 player and all you can hear is your music, you are causing serious damage to your ears. Turning the volume past the halfway mark is already too loud.
'Hong Kong people are already predisposed to hearing loss because of the rising level of noise pollution here and the fact that Cantonese is a loud language. If you damage your ears it is irreversible.' One in five Australians over the age of 15 experience some difficulty hearing. No such figures exist in Hong Kong, but Dr Li believes that the percentage in Hong Kong would be similar.
What is known is that the number of iPod users is increasing, with more than 200,000 portable music devices, including iPods, shipped to Hong Kong each month.
'The number of young people with hearing problems is severely underestimated. I think most people ignore things like tinnitus - a symptom of degeneration in hearing - unless it is so severe that they cannot sleep or perform,' she said.
Specialist John Woo Kong-sang said Chinese University was keen to carry out a study to see how loud portable music players can get and how many decibels each increment was equivalent to.
'Exposure to 90 decibels for eight hours a day can damage hearing but most people don't know the damage is exponential. An increase in volume of three decibels doubles the intensity,' said the honorary clinical associate professor at the department of surgery.
'A volume of 96 decibels two hours a day can damage your ears. The background noise on the MTR is about 80 decibels, so to clearly hear the music most people will turn the volume up to 90 or 100 decibels.'
Audiologists say most people speak at 60 to 65 decibels and argue at 90. A rock concert can get as loud as 150 - making ears ring. Long-term exposure to loud noises makes the ossicular muscles of the middle ear - which contract and cause pain when exposed to loud noise - lose the ability to contract.
Dr Li said: 'In the past, most people worked in construction or in factories and were exposed to noise pollution without choice. So now, at 50 or 60 years old, they are starting to lose their hearing.
'Today most of us are lucky enough to be white-collar workers and are less at risk. But now people are choosing to expose themselves every day to noises as loud as those at a construction site.'
A Sunday Morning Post straw poll of iPod users revealed little concern at the study's results. Shu Wing-cheung - who was blasting her iPod so loudly that most people in the carriage could hear it - said: 'Most people turn up the volume when they take the MTR. The point is to actually hear the music and not the train, isn't it?'