With the notable exception of Morrissey, who enjoyed a phase of appearing with his band the Smiths sporting a hearing aid, deafness has never been very rock and roll.

But all those years of turning the volume up to 11 are coming home to roost for the rock idols of yesteryear.

As lead guitarist with the Who, Pete Townshend often seemed dedicated to the art of aural recklessness, smashing his guitars to smithereens while revelling in the ear-splitting shrieks of feedback.

The Who also hit the record books in 1976 as the loudest pop group ever, after a concert which tipped the monitoring equipment at 120 decibels - the equivalent of a pneumatic drill - 50 meters away from the sound system.

Today Townshend is struggling with irreparable hearing loss. But rather than blaming the group's on-stage antics he believes it's down to his years of wearing studio headphones during recording sessions.

The guitarist, 60, says he fears for the "iPod generation" - his intuition tells him "there is terrible trouble ahead".

Others in the music world have also witnessed premature hearing problems. Phil Collins, Neil Young, Sting, Mick Fleetwood and the Beatles producer George Martin have all talked about their hearing problems.

There's even an organisation in the US called Hearing Education and Awareness for Rockers.

In the classical world, a third of orchestral musicians suffer hearing loss.

But a far broader concern is not for the hearing of ripened musicians, but, as Townshend himself suggests, the legions of earphone wearing converts to music on the move.

So should we be worried?

Such warnings have an air of familiarity about them for anyone who remembers the first incarnation of the portable music player - the humble old Walkman.

Unveiled by Sony in 1979, the Walkman spawned a host of imitators, and health warnings.

The advent of digital music players, with their capacity to hold thousands of songs and play for hours on end, has only increased the lure of listening to music on the go.

Sales of MP3 players soared by 200% in 2005 and the market for headphone entertainment continues to grow with portable video players and handheld games consoles.

But the trend has prompted concern from Britain's leading hearing loss charity, the Royal National Institute for the Deaf (RNID). It found 39% of 18 to 24-year-olds listened to personal music players for at least an hour every day and 42% admitted they thought they had the volume too high.

The risk is further heightened when using headphones in a noisy environment - busy High Streets or clattering trains for example - because listeners tend to crank up the volume to drown out extraneous sounds.

Such behaviour could lead to noise-induced hearing loss, say some experts.

The potential problem lies in the cochlea of the ear, which contains more than 15,000 specialised cells, sometimes called hair cells, that respond to sound vibrations and send signals to the brain.

"Each cell is tuned to respond to a different frequency in the sound spectrum," explains audiologist Angela King.

"These can be damaged by high volumes so that initially noises at higher frequencies sound smeary, then you can't hear them at all, and eventually the same happens at lower frequencies."

Under European rules digital music players are limited to a volume of 104 decibels. But that is significantly higher [see fact box above] than the 85-decibel workplace limit, which will shortly be reduced to 80 decibels.

Of course people tend to spend longer at work than listening to their iPods. But the RNID's Susan Duncan says the 85dB limit is a good guide.

"If it's uncomfortable to listen to or you can't hear someone talking at normal volume over the music, then you're listening too loudly," she says. The RNID is running an on-going campaign, called Don't Lose the Music, to highlight the risks.

Part of the problem with noise-induced hearing loss is that the effects may not become apparent for some years. Audiologists agree that despite concerns about personal stereo use in the early 80s, they are not yet seeing patients with such problems.

"It's a bit too early yet," says Angela King, who thinks the noise damage of loud discos and pubs is more of danger to young people than headphone use.

So what are the warning signs to look out for?

Anyone who has been to a nightclub or noisy concert will know the ear-ringing effect that can last for some time afterwards. It's known as a "temporary threshold shift" and, once in a while, is ok, says Jonathan Parsons, of the British Academy of Audiology.

But if the ears aren't allowed to rest between such bouts, the result could be a loss of hearing in years to come.

And just as technology has created such problems, so it may offer a solution.

Headphone maker Sennheiser this week launches its first "sound isolating" earphones for everyday consumers. Derived from the earphones that many performers wear on stage today, they block out extraneous sound so that music can played through them at quieter levels.

Unfortunately, those train passengers responsible for the relentless tinny overspill from their pounding headphones won't be able to hear collective sigh of relief of fellow travellers.

Source: http://news.bbc.co.uk/2/hi/uk_news/magazine/4580718.stm