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A reader wants to know how much damage personal music systems can cause to our hearing. I love my iPod and find it stimulating company. It provides a psychological boost at dull times of day and, if I am honest, is the only reason I still go to the gym. In my mind, this makes my iPod something that enhances my health.

I may be alone in thinking this. Such gadgets generally get a bad health press. In the US, there have been concerns about traffic accidents involving pedestrians who wear personal music systems. The BlackBerry – and again I love mine – is supposedly both addictive and capable of causing pain in the data-entering thumb. While the latter hasn’t occurred, I must confess to a mild form of addiction.

But should I be concerned about the potential dangers of personal music players or is this just another example of a society that is unable to cope with even the slightest risk? I’m especially interested because deafness is one of those conditions that doesn’t elicit much sympathy in spite of the fact that it can be invisibly disabling.

PubMed, the database of published medical trials, has some papers on the impact of personal music players. There is not an enormous amount of research on the nitty-gritty of how much and what volume will do irreversible damage to your hearing. It is, however, a significant research interest of Brian Fligor, director of diagnostic audiology at the Children’s Hospital Boston and an instructor in otology and laryngology at Harvard Medical School. I e-mailed him to ask if audiologists were concerned by the increased use of MP3 players.

“Yes, I am concerned,” he replied, “as I am with all potential causes of acquired hearing loss ... and occupational noise exposure. However, it’s important to note that it’s not the size of the earphone that matters, it’s the way in which people use them (how long they listen is much more important than whether or not small earphones generate higher sound level than bigger earphones).”

So what is the evidence that the use of such personal stereo systems is damaging? “My research, as well as several others, has demonstrated that all personal stereo systems have the capacity for over-exposure to high levels of music” says Fligor. Here is the crunch point. The sound levels that are capable of doing damage are easily generated by most devices. “All headphones can generate levels above 85dBA [the volume of noise measured in decibels], above 90dBA and most, at least, reach 100dBA. These are levels that could put a person at risk for hearing loss if they were to listen for long enough periods of time. This isn’t to say that no one should use headphones, just that there should be some acknowledgement that they can be used abusively, and an understanding of what circumstances tend to cause a person to use headphones abusively. For instance, listening to headphones while on a five-hour transatlantic flight could be problematic for a person choosing to listen near the maximum ... which some people do, according to one of my most recent studies.”

But how long is too long? And would restricting the amount of decibels produced by personal stereo systems – as is done in France – be useful in terms of tackling hearing loss? In France, public health law decrees that the limit for personal music players is set at 100dB, meaning that Apple had to change the limit for iPods being shipped to France. Fligor is refreshing on the subject. “I am vehemently opposed to level limiting, except that earphones should not exceed 115dBA [this is jackhammer kind of level]. I am personally a loud-music listener. I own an iPod and use in-ear headphones that can exceed 100dBA. If I were to choose to listen using iPod earbud headphones, which at maximum is roughly 100dBA (according to research not yet published but presented at conferences), then the longest I ought to listen is less than 15 minutes. So, if I were a consumer and I were told ‘these headphones are safer because they have a limiter set on them,’ I might be lured into a false sense of security and think that I can crank it up and listen as long as I’d like and I’d be protected. Nothing is further from the truth ... If I listen to 20 songs at max, I will have a temporary muffling of my hearing ... If I do this often enough, that temporary muffling is no longer temporary – it becomes permanent.”

In other words, listening too much to music that’s too loud can have an impact on your hearing sooner or later. Fligor says: “It’s OK to listen to loud music but moderate the time you listen. As well, you can fool yourself into listening at lower levels and still achieving the same enjoyment.”

This all sounds quite reasonable. My iPod, BlackBerry and I are off to the gym.

Margaret McCartney is a GP in Glasgow

margaret.mccartney@ft.com

More columns at www.ft.com/mccartney

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