An American podcast launched just eight weeks ago on a shoestring budget is attracting one and a half million devoted listeners each week, spurring talk of a coming of age for a medium often scoffed at by advertisers.
Serial is a sequential, radio-style documentary about a reporter revisiting and questioning details of the 1999 murder of a Maryland high school student and the subsequent conviction of her teenage ex-boyfriend.
It is also a smash hit. An average of 1.6 million people have downloaded and streamed Serial each week, and it was recently announced as the fastest podcast to surpass 5 million downloads on iTunes, according to Apple Inc. Yet Serial won't be heard anywhere on radio and Emily Condon, the series's production and operations manager, admits "We are literally sort of figuring this out as we go."
Even with a large audience, the business model paying the bills to produce an ambitious podcast is still tenuous and evolving. And the frenzy surrounding Serial hasn't yet guaranteed it will continue beyond its current story. The podcasting audience is still a small fraction of the size of radio's listener base, and sponsors have voiced concerns that many of the podcasts downloaded may sit untouched on computers and smartphones.
"A lot of the people who buy media look at podcasts and they say, well if you can't tell me how many people listen to the podcast and you can't tell me whether they actually heard my little sponsorship message or not, then I don't want to buy it," said Chris Boyce, executive director of radio and audio at the Canadian Broadcasting Corporation.
Nevertheless, many consider Serial a harbinger for the rapid growth of a hungry and vocal podcast audience. Ms. Condon said the podcast's creators have been genuinely surprised at the number of listeners it has hooked so quickly – it took years for Chicago Public Media's This American Life to reach its current average of 1.4 million weekly downloads.
"That seems encouraging, both for our project specifically, and just for the larger medium as a whole," she said, adding, "Our goal now is to see if we can make Serial be financially self-sustaining."
The program, a real-life whodunnit explored in host Sarah Koenig's conversational tone, was mounted "on a shoestring," though Ms. Condon would not give budget details. It is produced by four staff from This American Life in New York, with editorial advice from host Ira Glass, and started out with one sponsor, the e-mail marketing firm MailChimp. The Serial team even had to dip into a surplus from nearly 20-year-old This American Life to cover their costs, but they have since added a second sponsor to each broadcast and are now able to charge new advertisers more.
In terms of total listeners, radio is still dominant. But listeners increasingly expect their programs on demand, and as technology makes podcasts easier to access, they are seeing "exponential growth," said Eric Nuzum, vice-president of programming for NPR, the U.S. public radio giant.
But even at its highest levels, podcasting is less lucrative than traditional broadcasting, and Ms. Condon said Serial needs its own infrastructure to manage a second season, as continuing to cannibalize resources from This American Life is not an option.
Asking listeners to pay per podcast is one option that hasn't worked, and that has made public radio one of the largest sources of podcast content. "Would you turn on your local radio station to listen to a newscast and expect to pay for it? No, you wouldn't," said Angela Glover, a news media production specialist in Ryerson University's journalism program.
Appeals for donations have emerged as one revenue pillar for podcasts. Ms. Koenig began the latest episode of Serial, its ninth, with a question: "Do you want a Season Two of Serial? If so, I'm going to ask you for money. Maybe you saw this coming."
The other pillar is still advertising. Podcast sponsors typically pay between $10 and $30 per thousand listeners, according to Mr. Nuzum. But at the outset, audience estimates for a new podcast are effectively made up: Serial's creators estimated they would draw about 300,000 weekly downloads, and now have more than five times that number.
By most estimates, that means MailChimp has been getting a bargain on its Serial sponsorship. "We love Serial. The show has been a great success, so that's a wonderful impact for us," said Mark DiCristina, marketing director at MailChimp, in an e-mailed statement. "We don't really measure how it affects our bottom line, but we plan to continue supporting great ideas like Serial."
In recent weeks, Mr. DiCristina said on the podcast StartUp – which is about efforts by another former This American Life producer, Alex Blumberg, to build a podcasting company – that MailChimp is paying $6,000 (U.S.) per episode to be its sponsor.
Part of what drives that growth is "this idea of community and tribe around podcasts," Mr. Nuzum said, and that is starting to catch advertisers' attention. Already, multiple podcasts about Serial have sprung up, including The Onion's The Serial Serial and Slate's Serial Spoiler Specials.
"You see groups of people, whether it's 1,000 people who listen to a musical theatre podcast or something as big as Serial, it's a way for people to connect to a community," Mr. Nuzum said. "And that's the real power behind it, and that's also why sponsors are getting so interested."
NPR's podcasts were downloaded more than 69 million times in October. But it was only in the past year that podcasting "really [became] something that sustains itself," and even subsidizes radio in some cases, Mr. Nuzum said.
Podcasting is still a relatively small industry in Canada. Jesse Brown, a self-styled media critic, supports his Canadaland podcast with ongoing donations from supporters through the crowdfunding website Patreon. But the country's largest player is the CBC, with more than one million weekly podcast downloads.
The CBC is now "very bullish on the enthusiasm for podcasting," Mr. Boyce said. The corporation has experimented sporadically with creating exclusive podcast content and selling sponsorships, with limited success. Audiences were considered too small, and advertisers were wary. But Mr. Boyce now sees a shift under way.
"We're finally reaching a critical mass of people who are listening to audio on digital platforms," he said. "So I think the math on that is beginning to change."