Should content creators and advertisers alike be paying closer attention to podcasting?

Podcasting used to be viewed as a way to deliver super-niche content and to time-delay listening to public radio stalwarts like “This American Life” and “RadioLab.” But the record-breaking popularity of “Serial” last year may have blown the whole industry open.

Hosted by reporter Sarah Koenig, it spend 12 episodes investigating a 15-year-old murder in Baltimore, casting doubt on the conviction of Adnan Syed. The staggering popularity of the show took many by surprise. It was the  top podcast in the U.S., Canada, U.K. and Australia, and in the top 10 in Germany, South Africa and India. According to Edison Research, 39 million Americans listened “Serial” during just the last month of its first season.

So was the popularity of “Serial” just a fluke, or the marker of a cultural shift?

Until “Serial” came along, podcasts had largely “slipped marketers’minds” Wall Street Journal columnist Steven Perlberg wrote. ZenithOptimedia, a marketing agency, forecasted 0% growth in 2014 in podcasting.

The numbers tell a different story.

According to the Washington Post, podcast subscriptions on iTunes passed the 1 billion mark last year. Monthly listeners number 75 million, up 25% last year. Today, podcasts comprise 30% of the audio Americans listen to (“Audio” was defined to include recoded music, radio, TV music channels, podcasts, streaming audio, and Sirius XM).

New York Magazine also noted that podcasts are demanding higher ad rates: $20 to $45 CPM (cost per 1,000 impressions, a standard ad-industry unit). The average radio CPM is $1 to $18, network TV is $5 to $20, and web ads are $1 to $20. Podcast advertising network Midroll surveyed 300,000 listeners and found that 63% of people bought something advertised on a podcasts.

Ease of access to podcasts will likely boost the audience, too. The proliferation of smartphones, cellular data plans, wireless bluetooth speakers, and integrated car audio systems all have made podcast listening easier. GMSA, an independent research group, estimates that 50 percent of all cars sold in 2015 will be internet-connected, and 100 percent by 2025.

The remaining challenge for podcasts is providing reliable audience metrics in order to attract more advertisers. Right now, podcasts still do not have real-time data or specific demographic data on listeners, unlike other online advertising or digital audio streaming services. Advertisers can track the number of downloads, there still isn’t a way to determine whether a podcast was played to the end. If podcasts continue to grow in popularity, marketers will be clamoring to find a new ways to unlock those metrics.

Not a podcast listener yet? Below a is a list of some Team ZEITGUIDE’s favorite podcasts to get you started:

Marketplace – Business
Nerdist– Comedy
WTF With Marc Maron – Comedy
My Brother and My Brother and Me  – Comedy
99% Invisible – Design
Food is the New Rock – Food
Afropop Worldwide – Music
KCRW’s Left, Right & Center – Politics
Here’s the Thing (with Alec Baldwin) – Society & Culture
Stuff You Should Know – Society & Culture
Slate’s Hang Up and Listen – Sports
This Week in Tech – Technology

Keep learning,

Brad Grossman and Team ZEITGUIDE