What's the soundtrack of your life?

The fragility of cool can be an unnerving thing. In a recent issue of Wired magazine, journal of record for cyber-geeks and early adopters, you could have found two small articles. One was the magazine's long-running filler What's On Your iPod? - a kind of Desert Island Discs for the internet generation that asks owners of Apple's portable music player to reveal the top 10 items on their playlist (an occasion for much eclectic one-upmanship). The other article was the magazine's regular feature Wired/ Tired/Expired, a barometer of changing cultural weather. In this it was suggested that the iPod is now officially Tired, keeping company with the word "memepool" and the band The Stills. All it takes is the turn of a page for an object to move from being a badge of consumer aristocracy to the mark of the man who has arrived too late.

Apple executives should be thrilled. Moving from Wired to Tired is proof, were any needed, that the iPod has burst out of its niche and is headed for a mass market. The iPod enthusiast who compared the machine to a samurai sword ("a portable symbol of status, power and class") might not like it, but the Companionship of the White Wires is getting less and less exclusive by the day. And the American success of Apple's revolutionary music-marketing system the I-Tunes Music Store - designed to feed voracious iPods -- has already prompted others to offer similar websites. My Coke Music may have fallen flat on the first day after problems with the technology, but it is up and running now, offering consumers the opportunity to buy a huge number of single tracks for just 80p. The iPod, too, has had its technical teething problems, but it seems almost certain that the old models for selling music are likely to find themselves slowly squeezed out of existence as hardware and the software converge. And that means that the way we think and feel about music is, once again, bound to change, too.

In one respect the MP3 players are just an old revolution reheated. It does what the Walkman did, but better - allowing anyone who owns one to compress a lifetime's music into something the size of a cigarette packet. This feels more like magic than electronics, to be honest, and it means that the Walkman's well-established trick of supplying a soundtrack to life now has a vastly expanded repertoire. You don't have to ferret in a bag for a new mood (if you'd remembered to bring it with you in the first place). You just dial it in. You can even create your own playlists for every eventuality: Train Stopped in Tunnel, say, or Checkout Queue Blues. Internet sales of music, on the other hand, introduce a genuine novelty; the ability to acquire music on a pick-and-mix basis.

Naturally enough, all of these developments are presented to us as unalloyed benefits, and it's often quite difficult to think of them in any other way. High-quality music, on tap and on the go, is one of the more conspicuous privileges of modernity. It makes Renaissance princes of us all, capable of commanding orchestras on whim - and making them play in places that no orchestras would be prepared to go. In a recent episode of ER, Carter pulled out his iPod in a Congolese war zone and had Les Nubians run through a couple of numbers for him - not a gig they'd be likely to take on for real. But such indulgences also have a hidden cost. You might put it crudely like this: whenever the consumer gains power the art, or the artist, loses a little.

We will never know, for example, what it is like to hear music as a rare luxury, to have it pierce through an otherwise mundane soundscape with something transcendent. True, personal music players allow us to overlay the banal with the sublime whenever we want, but sublimity can't survive prolonged contact with banality without suffering a little. Listening to the "Eroica" in a crowded concert hall, in the knowledge that you may not get another chance for years, is very different to listening to it on your own while waiting for the 8.32 to Victoria. Even the development of one-song purchases changes the rules of engage- ment, by allowing customers to fillet an artist's work for what they think of as the white meat.

And while we might be happy to let the concept album pass away without mourning, what happens to that rogue track you begin by hating and slowly come to appreciate because you're too lazy to hit fast forward or lift the needle? There's no going back now - and I doubt anyone would want to - but it's worth remembering that our subjection to art, the necessity for us to surrender and submit to its demands, is inevitably diminished by its subjection to our whims.