Noted American novelist William Gibson once described the Sony Walkman as "having done more to change human perception than any other technology".

He was referring to the possibility of the user transforming any landscape passed through at will, in effect creating their own personalized "soundscape".

Sony had unwittingly tapped into a range of deep-seated cultural desires in creating the Walkman in 1979, the first truly privatized and portable music machine. Never before had consumers been able to create their own very personalized soundworlds while on the move in virtually any situation.

The interesting question becomes why would many of us want to replace the sounds of our environment with our own very own soundtrack?

Urban theorists have often perceived industrial cities as places from which people want to escape. Not only are they often crowded, denying us our sense of private space but they are also often anonymous – we tend to be lost in a sea of faces. Cities are both potentially exciting but also often alienating places. Yet this desire to retreat from the sensory overload of the city is just one explanation for the success of mobile sound-technologies such as the Walkman and now the iPod. To be sure, many iPods users like to block out the experience of travelling on overcrowded tubes each morning, but equally, also use them in deserted urban streets.

Creating your own private acoustic space indeed pre-dates the Walkman; early radio users in the 1920s often listened to their radios at home using headphones, even listening to your sound system at home while on your own is to create your own soundworld. With the advent of recorded sound, music has played an increasingly important role in consumers' lives.  Many of us construct our own narratives to significant songs, making those songs  'our own' and indeed culturally we increasingly define ourselves through our musical taste.

Equally we learn to experience more and more things to the accompaniment of music with our homes becoming more like sophisticated recording studios each year. We do most things to sound accompaniment, either to the sounds of the radio, television or sound system. The pre-conditions for wanting our own sounds to accompany us wherever we go are put in place through our home listening habits.

What then does this tell us about ourselves? Well, first of all that many of us like to be able to control our own experience and sound is the most successful way to do this. Users always tell me that their experience of moving to their own soundscape is one of the most pleasurable activities of their day.

Using an iPod enables users to manage their mood successfully, if they are happy they put on happy music, if they are melancholic they play music to enhance that mood. If their journey to work is boring they reclaim that time and make it they're own - commuting becomes a pleasurable experience. If they want to think about what they did on their holidays, then carefully chosen music places them  'cognitively"' back on holiday. If they don't want to think about anything at all then they can just lose themselves to their chosen music. In doing so users re-possess the places that they pass through in order to make them conform to their desires.

Through the power of sound the world becomes intimate, known and possessed. iPod use points to the power of sound to root users into the world so successfully that they listen to our own 'soundtrack' to life more and more frequently. Since 1979 they have had the ability to make the world appear to them, as they want it to.

We can think about this cognitively (how do users manage their moods), aesthetically (how they make their journeys into their own movies) and morally (how they manage their interaction with others, do they take out those earplugs when  having to talk to someone for example?). iPods enable users to take these desires onto another plane.

The ability to take their whole music collection with them and stream it to a range of moods enables users to know that they have music for all occasions, unlike the Walkman user who was often stuck with a few tapes - and users know that no music is better than the  'wrong' music.

Yet in some ways iPods are rather more social than Walkmans - they are not just the ultimate privatization machine. Users can also share music with friends, plug it into the car and play music for the whole family and use it as a jukebox for parties at home.

Like mobile phones, iPods tell us that many of us only want to have contact with those people we already know. That many of  us prefer to create our own very warm and friendly bubble of experience in a world that becomes increasingly anonymous and cold for us. "To each their own bubble" becomes a potent metaphor for 21st Century urban experiences.