Spotify is testing out a new interactive voice ad format, allowing users to engage with sponsored messaging on the streaming music service.

If a user opts-in to allow microphone permissions in the Spotify app, they could receive an ad promoting a sponsored podcast or playlist. The ad would encourage them to listen, asking them to play it now. If the user responds in the affirmative, the sponsored content will play. If not, the ad break continues.

The company began testing the voice ads last week, with Unilever brand Axe and Spotify Studios promoting the original podcast “Stay Free: The Story of The Clash.”

The test marks a new effort by Spotify as it seeks to bolster its ad revenue. Despite more users being on the free, ad-supported tier of service, advertising only accounts for around 10% of company revenues. 

Spotify is turning to podcasting and new ad formats in an attempt to close that gap.

The company has been on a spending spree, acquiring a number of podcast studios and platforms. It has released new advertising opportunities, such as sponsorship of its signature playlists.

Still, voice ads mark a logical step for Spotify, with its emphasis on audio. Many of its users are listening on a device with a built-in microphone. The big question is whether advertisers will sign on, and how they will take advantage of these new opportunities.