Has the iPod made us anti-social?
It's 10 years since the iPod was unveiled, but has the MP3 player turned us all into headphone-wearing, anti-social people?
It sounds like a dystopian vision. Half of humankind wired up to a parallel universe that leaves them oblivious to their surroundings and fellow man.
Those used to travelling on public transport will recognise the scene - a carriage full of commuters sprouting white wires that plug into the ear with little white buds. In the car, children listen to their own music on headphones.
Once upon a time footballers travelling to away games would bond over a game of cards on the team bus. Now they step off the coach with headphones on, as if their journey has been a solitary exploration of a favourite playlist or movie. Many runners, cyclists and even swimmers train with headphones.
The personal stereo has been around for three decades. But the iPod - by far the biggest selling MP3 player - has taken it well beyond the limitations of its bulky earlier equivalents, like the Sony Walkman or Discman. Since Apple unveiled its first iPod in October 2001, promising "1,000 songs in your pocket", the company has sold more than 300 million of them.
In 2005 the media greeted the revelation that President George W Bush owned an iPod with surprise. Now that the iPod's tentacles creep through society, such news would be greeted with a shrug.
By 2007 over half of Western city dwellers were using an iPod or MP3 player, says Prof Michael Bull, author of Sound Moves: iPod culture and urban experience.
It has gone beyond the anti-establishment youth market of the personal stereo to embrace everyone from children to grandparents. And research suggests that when people switch to an MP3 player, they listen to music for twice as long as before, Prof Bull says.
Leander Kahney, editor of Cultofmac.com, based in San Francisco, argues the iPod has enriched people's lives, allowing them to escape the daily grind. "It's been a great boon to people on the way to work. There's nothing like music to be a mood lifter. The iPod is a mood drug."
And despite attempts by competitors like Microsoft to launch their own versions, Apple's product has not had significant opposition, never slipping below 70% market share, Kahney notes.
German-Brazilian inventor Andreas Pavel can be regarded as the spiritual father of headphone culture, having invented the first personal stereo in the 1970s. Pavel's initial aim was to free recorded music from the yoke of the household music system.
But when he first tried out his prototype - "this magic combination of sound source and headphones" - he experienced something transcendental. "It was like a dream. It is the pleasure of the music combined with the vision of your environment. You are putting a soundtrack to life so that it becomes like a film."
In those days he was laughed at for wanting to move around while listening to music on headphones, he recalls. And Sony's marketing department told him his prototype was too expensive and wouldn't find a market.
But they later went on to develop the Walkman. In 2003, after 23 years of legal negotiations with Sony's lawyers, the Japanese electronics firm agreed to settle out of court.
So ubiquitous is headphone culture today that it has become a sort of cultural shorthand - often for a spoilt, selfish generation who lack civic values.
When British sailors were taken prisoner by the Iranians in 2007, Able Seaman Arthur Batchelor admitted he had "cried like a baby" after his iPod was confiscated by his captors. He was branded a national embarrassment by newspapers. In the same year, a Muslim juror was discharged from a murder trial after being caught listening to her iPod under the hijab.
But the most visceral concern is that the iPod is making people anti-social. It's not just the tinny noise that leaks out of the puny ear buds but the barrier the device erects between people. Telegraph columnist Bryony Gordon says young people have grown up to be "plugged in" to their iPod, rather than relating to their surroundings.
"I wouldn't stop someone wearing those white wires to ask for directions. It's like they're putting up a big closed sign," Gordon notes.
Prof Bull's interviews with iPod users confirm this perception. Many iPod users told him they resented people interrupting their listening to talk to them.
The iPod has thus created a minefield over how to behave. When entering a shop, should the user take off their headphones to talk to a sales assistant? Should they take one out? Or leave them both on and turn the volume down?
Debrett's etiquette adviser Liz Wyse says that both of them must come out. "It's very belittling to a shop assistant if you can't be bothered to take your headphones out. And the half on, half off, look is compromised - it's like you're going to put them back in any minute."
But in a reflection of what a battlefield public space has become, she defends the iPod as a means of defence against a still worse public nuisance - the mobile phone. "An iPod is a brilliant thing on trains. Otherwise you're forced to listen to people's loud conversations on their mobile phones."
Psychologist Oliver James says the reluctance to take one's headphones out shows the "self-absorbed and atomised" state that people have got themselves into. "It's almost like madness. Will I come out of my bubble? How much of a compromise will I make to my external reality?"
But the fact is, it fits our modern desires, says Prof Bull. People have never talked much on trains - hence the famous commuters' trick of hiding behind their copy of the Daily Telegraph. The iPod is merely amplifying that trend.
"It can be lonely travelling through public space and using music warms it up," he says. The downside is that while the individual feels warmer - and has the perception of being safer despite not being able to hear an approaching assailant - the public realm becomes a less social, "chillier" space.
But the iPod hasn't caused this move from public to personal space, it is just reflecting the trend, Prof Bull argues. Nowadays people work out to their own playlists in the gym rather than hearing the same tunes. But that's not to say people are becoming anti-social.
"The actual presence of people next to you in the street is not recognised as social any more. We get our intimacy from nearby loved ones or people who are absent over chat sites and social media," he says.
Pavel says he never set out to isolate people from the outside world when he made that first rudimentary personal stereo. Indeed he recalls how his patent suggested a non-recording microphone so that users could hear the world around them during the music. And there were to be up to four outputs so that people could listen in groups.
In the end, it's a trade-off, Pavel believes. Sometimes we want privacy and escapism, other times interaction with our fellow man.
"It is somewhat isolating. But when I'm on the bus I don't necessarily want to talk to people. I want the aesthetic involvement of listening to music."