After Serial and S-Town, will podcasts ever really catch on?

S-Town, the gripping saga about life and death in Alabama, is the latest podcast to have notched up impressive listening figures. But podcasts on the whole still don't seem to be breaking through to the mainstream.

Have you ever downloaded a podcast? And, if so, did you actually listen to it?

Podcasts have long been seen as the future of radio, a great way to pass the time on a long commute or catch up on a radio show you've missed.

They've been growing in popularity since the early noughties, when Apple's iPod first hit the market ("podcast" is a cross between the words "iPod" and "broadcast").

But 15 years on, they remain a relatively niche pursuit.

"I don't know whether podcasting is a mainstream proposition," says Matt Hill, co-founder of the British Podcast Awards.

"Its core strength at the moment is in narrowcasting. It creates audio content for niche groups of people, but it does so really effectively."

According to Rajar, the body that monitors radio listening, 9% of adults in the UK say they download podcasts per week - around 4.7 million people.

Which is a fair few - but not much compared with the 90% (or 48.7 million adults) who listen to live radio every week.

Kate Chisholm, radio critic for The Spectator, says: "Podcasting is arguably something for metropolitan people, maybe in their 20s and 30s.

"I don't think it's something that particularly seeps out to the mainstream. On one level I would say that's changing, but then how many people who live on my street would be downloading podcasts? I'm not sure it would be very many.

"They'd listen to Classic FM or Radio 2... but a lot of people look at me blankly when I mention Serial."