This feature is not currently rolling out widely—it's available in search labs, which means you have to manually enable it. Anyone can opt in to the new Audio Overview search experience, though. If you join the test,

Google is rolling out a test that puts its AI-powered Audio Overviews on the first page of search results on mobile. The experiment, which you can enable in Labs, will let you generate an AI podcast-style discussion for certain queries.

Google is testing Audio Overviews for specific search queries, utilizing its latest Gemini models to enhance user understanding.