The cultural changes wrought by the iPod and the MP3-trading movement are now well known, but here’s something to add to the list: It seems that radio listening habits—or at least online radio listening habits—have been deeply affected as well. At a recent staff meeting at WFMU (where I do a regular music show), the station manager shocked most of us by urging all DJs to change the way our archived programs are accessed over the Internet. Instead of the default format, where we offer just a single link to each two- or three-hour show, he strongly recommended that we make our archives accessible by individual song. The newest generation of music listeners, it turns out, is almost completely song oriented and is far more likely to click on a radio archive to hear a specific tune (as found on our online playlists, using a search engine) than to sit through the entire show, no matter how brilliant the whole may be.

In retrospect, the reasons for this change in orientation are obvious: On top of a general decrease in attention spans, most of the generation of music listeners coming of age in the past five years thinks of music as collections of MP3s—that is, as individual tracks—swapped with friends, downloaded off the Net, or purchased from online music stores, then listened to on a computer or MP3 player, possibly in random shuffle mode. The basic unit of music consumption is now the file, rather than the album or CD. Nevertheless, this development has come upon most creative radio producers as a rude surprise. Having been suckled on the “freeform” radio tradition, we tend to view our shows as almost indivisible entities, even more than performers of live music do.

In freeform radio—a rapidly dying format, sadly, simply because it’s not calculated enough or bad enough to survive in the Free Market—the segue is what matters. A freeform DJ generally views his or her show as an organic whole, with the transitions between songs the crucial connecting tissue holding the whole thing together. You may go from koto music to the New York Dolls to free jazz in the course of an hour (which is the kind of thing freeformers are proud of), but it’s how you get from A to B that counts. Anybody can throw Too Much Too Soon on turntable 1 and Albert Ayler on turntable 2 and call it a day, but creating something that holds together, catches subtle and unexpected connections between tracks, and creates some kind of unified mood (or a shifting sequence of moods) is what a great set is about. You may have a kickass record collection, but just slapping things on the air in effectively random order—where’s the art in that? And what listener wants to be dragged through a jolting cacophony of loud–soft–acoustic–electric–spoken word–folk–world music–comedy, like barreling down an unpaved road in a VW Beetle for an hour and a half?

Segues aren’t explicitly talked about very often even by DJs. And there are situations where it’s not even necessary to think about them, like an all-garage-rock show or an all-gamelan-music show, where they just happen naturally. There’s also nothing wrong with wanting to simply hear a particular song you love now and again. But the importance of segues in music sets can’t be stressed too much. In the days when I first auditioned for a radio show (and later screened other prospective DJs), audition tapes were made with most of the body of each track removed, leaving just the segues and the few seconds before and after each transition. Once it’s been revealed which track the DJ has chosen to go to after the current one, the rest is more or less an anticlimax, at least when you’re evaluating the person’s chops. It’s not just your musical vocabulary and taste that matter, but the ability to put it all together in some meaningful way. Having a listener give you three hours of valuable time to spin absolutely any music in the world for them is both a privilege and a challenge, and creating some kind of unique sound environment for them (and this applies to rock and roll just as much as more obvious genres, like ambient or soundtrack music) is about the best thing you can do in return. The idea of “psychogeography” is no less important in a set of music than in an experimental film or an actual psychogeographical drift through a physical space.

But back to iPods and file swapping: With MP3s becoming the de facto currency of music listening and trading, and with shuffle mode becoming a more and more common way of programming an hour of music—Apple’s recent introduction of the iPod Shuffle is pretty clear evidence of that—the art of the set and the segue is in imminent danger of dying. As a DJ in his forties, I’m aware of the risks that saying this kind of thing entails, but I’m not simply dismissing the younger generation of listeners as a bunch of Xbox-playing philistine punks. In fact Top 40, with its purely single-song-oriented approach, dates from long before freeform radio. It’s interesting to note that the earliest rock and pop music listeners, with their carrying cases of vinyl 45s, were strikingly similar to today’s MP3 collectors; freeform radio was originally a product of the late-1960s post–Sergeant Pepper era, with the blossoming of LPs, eight-minute-long tracks, and “serious” listening. Today, with the staggering variety of recordings of every conceivable style and provenance available (a situation only helped by MP3 technology and file swapping), and the ease which they can be combined—sometimes literally, in the case of mashups, which can almost be thought of as vertical segues—we have the opportunity to create greater meta-masterpieces than ever, tailored to people’s moods, or the time of day, or the weather. Why destroy all that by getting lazy and pushing the “shuffle” button?