Each afternoon, stay-at-home dad Dan Klass waits until his young daughter falls asleep and then dashes into a home-office that doubles as a broadcast studio.
Hunched over a microphone, the former stand-up comedian uses the quiet time to record his very own amateur talk show titled "The Bitterest Pill." After an introductory tune that sounds like a mash-up between a mariachi band and the funk bass of the "Seinfeld" theme, the Los Angeles native launches into a breathless, free-form soliloquy that encompasses subjects such as child-rearing, politics, and an embarrassing encounter with Meg Ryan at a party. It ends when his daughter stirs in the next room.
Mr. Klass's month-old program is hardly a conventional radio show. For starters, it isn't broadcast on any of the nation's airwaves. Instead, Klass transmits his show in a format called "podcasting," a new Internet-based medium that has the potential to revolutionize the content of traditional radio as well as reshape our listening habits.
The idea behind a podcast is simple, yet brilliant. Instead of using portable MP3 players such as the iPod only for listening to music, new software called iPodder allows one to download prerecorded radio shows onto the devices.
Though several radio stations have begun podcasting shows, the medium's most visible impact has been empowering DJs like Klass to broadcast their own homemade radio shows with just a microphone, a computer, and a dash of brio.
"Aspiring writers and journalists have their blogs, aspiring movie directors have their Apple iMovies, and aspiring DJs/radio producers now have podcasting," says Reinier Evers, the founder of trendwatching.com, in an e-mail interview. "Podcasting allows for tens of thousands of new 'radio' stations - or, more likely, tens of thousands of radio programs."
It's a boon for audiences, too, because podcasting is the audio equivalent of TiVo. Once a listener logs onto an individual podcaster's website and signs up as a subscriber, each new program will automatically download to his digital player. That frees people to listen to shows on their schedule rather than the broadcaster's.
Podcasting is a radical way of looking at radio, says Tod Maffin, a technology futurist and producer at Canada's CBC radio.
"Instead of me listening to a single radio station for an entire day and picking up a dozen things that interest me, wouldn't it be great if I could tune to all of the world's public broadcasters and specify the particular types of content that I'm interested in," says Mr. Maffin.
Although the software that makes podcasting possible has been publicly available for only three months, radio stations are already exploring ways to exploit the medium. Several National Public Radio stations have been swift to make a few shows, including "This American Life," available as podcasts. Air America and the British Broadcasting Corporation have also launched their own podcasts.
For the most part, though, the medium's pioneers are do-it-yourselfers - people like Klass.
Five years ago, the L.A. podcaster did research on the requirements to set up a tiny radio station.
"The costs, obviously, are astronomical. And that's assuming you can find open space on the dial," says Klass. "When I heard about podcasting I thought, 'Oh my gosh ... I don't have to get permission from the FCC. I don't have to elbow in between Clear Channel and Clear Channel.' "
"The Bitterest Pill" benefits from smooth DJ banter that comes from Klass's prior experience at an FM college station. But most podcasts sound more like radio versions of public-access cable than like Garrison Keillor.
A quick browse through podcast directories such as ipodder.org or podcast.net lists shows that range from amateur radio plays and poetry readings to movie reviews and shows devoted to car talk. One can subscribe to podcasts such as "Coverville," a show devoted to odd and obscure cover versions of well-known songs; "Daily Grind Coffee," a peek into high school life by a teenager who'd rather be podcasting than doing homework; or "Folkden," a roots-music podcast hosted by Roger McGuinn, onetime guitarist for the Byrds.
Of course, there are dozens of podcasts in which cyberspace versions of Jack Handy ramble on with deep thoughts about life, the universe, and everything. That's hardly surprising given that many of the early adopters of podcasting are bloggers who are now creating, in effect, audio blogs. Like the popular online journals that have exploded on the Internet in recent years, podcasts are often informal, untidy, spontaneous, and diverse in scope.
Though podcasting is dominated by talk, the MP3 medium may prove to be a vital force for music.
At present, terrestrial radio stations tend to structure their playlists to offend the least number of people so that audiences will stay tuned for the next group of commercials. That format has alienated listeners who crave more eclectic, less predictable fare on the airwaves.
Chris MacDonald, founder of Indiefeed, is optimistic about podcasting's potential to become an alternative to traditional music radio. His website allows subscribers to sign up to receive free, single-song podcasts by independent artists in genres ranging from hip-hop to blues. Each song is preceded by a brief introduction including information on where to purchase the artist's music.
"There's a variety of places you can spend time learning about new, uncovered music," says Mr. MacDonald. "But what we realized is that there are very few places where it's distributed in an automatic fashion."
Podcasters who develop a reputation for playing innovative, cutting-edge music will become trusted intermediaries between the listener and musician, says Dave Winer, a creator of the iPodder software.
Many observers expect podcasts to become as diverse and niche-oriented as the world of blogs. In theory, listeners will be able to pick and choose from a menu of shows that cater to their interests. They'll also be able to subscribe to downloads that provide news from the stock market or updates on developments in a particular industry. And one will soon be able to access podcasts on a standard-issue cellphone.
"I venture there's about 33 million MP3 players out there, and after Christmas when everyone has their new cellphone, there's another 600 million cellphones that have MP3 capability - and they have a network connection," says Adam Curry, who along with Winer developed iPodder.
Mr. Curry believes that these developments will challenge the dominance of terrestrial radio.
Maffin agrees that podcasting will shake up radio - but in a good way. The download medium provides stations with a new outlet for their shows. If the content is good enough, stations may even be able to charge consumers for downloading individual shows, just as some listeners now pay a premium for satellite radio.
There's a term that sums up the future of podcasting: niche radio.
On terrestrial or satellite radio, one can tune into a dozen formats or maybe even five dozen formats. But with podcasting, everybody is a format of one, says Jesse Walker, a managing editor at Reason magazine and author of "Rebels on the Air: An Alternative History of Radio in America."
"Podcasting is just making it easier for this new set of niche listeners and this new set of producers to find each other," he says.