Podcasting is an emerging market that’s moving mainstream.

More than a quarter of people in the U.S. (73 million) listen to at least one podcast a month – and half of them have an annual income of $75,000 or more. Fifteen percent of these listeners earn $150,000 or more, according to Edison Research.

“Listeners are gravitating toward spoken word content,” said Lizzie Widhelm, Pandora’s senior vice president of ad innovation and sales enablement, in an Ad Exchanger interview.

With people in the U.S. listening to podcasts at rates that are up 40 percent since 2017, it’s time to consider the podcaster a true influencer, said Harvey Schwartz, co-founder and executive vice president of talent at WhoSay, a Viacom company that creates influence marketing campaigns for brands.

“Podcasters have fans, not followers,” Schwartz wrote in a WhoSay blog. “The relationship with their audience is unique in today’s fandom society.”

Briahna Gray is a podcast host with a loyal audience and has online programs including NPR, TYT, and The Real News. She talked about the “intimacy of audio” with Backyard Media:

“Podcasts are strangely intimate,” Gray said. “You really do feel like you’re in a relationship with the podcaster.”

The largest digital audio platform in the U.S., Pandora is betting big on podcasts. It wants to fix podcasting’s discovery problem with its Podcast Genome Project. In September, Pandora got a vote of confidence from SiriusXM with a $3.5 billion acquisition offer .

Pandora wants to provide easy and effortless access to podcasts. “Nailing the personalization piece is going to set us apart,” Widhelm said.

Pandora is building for podcasts “what we did for music, which is the podcast genome,” Pandora CEO Roger Lynch told The Verge earlier this year.

The Podcast Genome Project, due to launch later in 2018, is intended to help people find podcasts that interest them. Better discovery by users means more advertising. It opens up greater opportunities for brands to target relevant audiences, WARC reported.

In addition to traditional sponsorship, Schwartz said he recommends advertisers activate a 360-degree campaign with the podcaster talent as the influencer, and use paid media through their social channels to effectively target a desired audience.

“Given we’re on the bleeding edge of market adoption, this might not seem an easy activation; however, the upside in overall performance will make the rewards well worth the effort,” Schwartz wrote.

Podcast advertising is at a tipping point, Schwartz said in a blog.

“30 percent of agencies and brands (are) currently advertising through podcasts, while 36 percent said they are likely to do so in the next six months. There’s no shortage of inventory, with now over 550,000 podcasts.”