Podcasters love YouTube. That’s making podcast advertising less predictable.

Subscribe to enjoy similar stories. Podcast ads may be better heard than seen, a new study suggests, even as the popularity of video podcasting skyrockets. Host-read podcast ads on YouTube are up to 25% less effective at driving purchases than in audio-only environments, according to research on more than 1,000 campaigns that was conducted by the marketing agency Oxford Road and the audio measurement firm Podscribe.

That could partly reflect consumers’ differing mindsets with each format, said Giles Martin, executive vice president of strategy at Oxford Road. Listeners on platforms like Apple Podcasts and Spotify tend to deliberately select shows, whereas YouTube audiences sometimes arrive via algorithmic suggestions, Martin said. The listening experience can also be more intimate and immersive than the bustling, brightly lit environment of YouTube.

“With YouTube, a medium with a screen, you have thumbnails, other options competing for your attention and encouraging you to click away," Martin said. “So if your attention isn’t immediately grabbed within the first 30 seconds or the first two minutes, it’s very, very easy to lose viewers." Google said in response that advertisers on YouTube already recognize the differences between audio-only services and its video ad offerings. But ad spots in video and audio-only podcasts are often sold the same way, through the same channels and at the same price, Martin said.

And Google’s longtime walled garden approach to measurement makes it difficult for advertisers to track campaigns consistently across video and audio-only channels, he added. For the best part of two decades people consumed podcasts just by listening, and podcasters produced shows without a camera in sight. But