According to the American think tank Brookings Institution, based in Washington, which has analyzed tens of thousands of episodes, it is the program "War Room" of the former adviser to Donald Trump, Steve Bannon, which wins the palm of the greatest number of erroneous allegations, especially about the presidential election of 2020.

As for Joe Rogan's ultra-popular podcast, number one on Spotify, he praised the effectiveness -- unproven -- of certain treatments against Covid-19.

The danger of this type of content lies in the fact that listeners seek programs that reinforce their own beliefs, but also in its almost intimate conversational format, experts say.

"There's something inherent in the relationship between the host (of a podcast) and the audience that confers that degree of credibility, trust," says Valerie Wirtschafter, the data analyst who led the Brookings Institution study.

"And the challenge is of course that everyone can start a podcast, everyone can get a microphone and tell what they want."

Valerie Wirtschafter and her team analyzed 36,000 episodes and found that 70% of the most popular American podcasts had relayed at least one allegation identified as false by verification agencies. A lot of this fake news was about the 2020 U.S. election and Covid-19.

Listeners have little or no opportunity to comment on podcasts or denounce misinformation, which "facilitates the spread of false, misleading or unsubstantiated content," the Brookings researchers wrote in their February report.

Joe Rogan depublished an episode in January in which he referred to a fake tweet about Covid vaccines falsely attributed to a Florida doctor.

But this type of action is very rare. And moderating that content is "really complicated" for tech companies, Wirtschafter said.

Auditors' confidence

According to an April Pew Research Center survey, about half of Americans listen to podcasts, with 87 percent saying they expect rigorous information, a higher proportion than other media.

Illustrative photo of a phone displaying Joe Rogan's podcast, "The Joe Rogan Experience," in Washington on February 7, 2022 © MANDEL NGAN / AFP/Archives

"It's like having a one-on-one conversation: you feel like (the podcast host) is talking to you. People trust more, hence the greater impact," says Sylvia Chan-Olmsted, director of media consumption research at the University of Florida.

Steve Bannon and Joe Rogan did not respond to questions from AFP, but Bannon told The New York Times he was "honored" to be on the list and consider his broadcasts to reflect the "truth".

Responding to misinformation in podcasts can be complicated because this ecosystem is deployed on multiple platforms with varying moderation rules.

Spotify, for example, bans "dangerous" content but also seeks to "respect the expression of creators" like Joe Rogan, whom the company supported in 2022 when he was accused of misinformation about the coronavirus.

NewsGuard, a company that evaluates the credibility of websites, will expand its business to some 200 podcasts in 2024, alerting listeners and advertisers.

For its editorial director, Eric Effron, such a project is however "more complex" than evaluating websites, because the audio format requires listening to podcasts and analyzing their transcription.

"It requires a huge investment because we employ human intelligence," he said.

The question of responsibility in this area is not obvious either: some point the finger at the platforms, others at the recommendation algorithms of tech giants such as Apple or Google.

For Valerie Wirtschafter, "unpublishing may not be the best solution" to improve the quality of information. "But I think adding context, providing a richer environment for people to analyze the facts and talk about them could be extremely helpful."

© 2023 AFP