An IAB report finds that digital audio — defined as podcasts and streaming for music and radio — had the largest year-over-year growth rate compared to streaming video and social media advertising.

Podcasts and streaming for music and radio has seen the largest growth in ad revenue, hitting a total of $4.9 billion in revenue during 2021, according to a report from the Interactive Advertising Bureau released Tuesday.

With a nearly 58 percent year-over-year growth in ad revenue — up from 13 percent the previous year — the digital audio category outpaced streaming video, social media, search and display advertising growth during 2021, the report found.

The majority of growth in the digital audio category came from mobile devices, which brought in $4.1 billion in ad revenue and accounted for 85 percent of the category’s total revenue. Revenue on desktop devices for digital audio paled in comparison at $739 million, the report said.

But in terms of total dollars, search continued to drive the most revenue for the year at $78.3 billion, followed by display advertising at $56.7 billion. Digital video was the third-largest ad revenue driver, bringing in nearly $40 billion in 2021, representing a 51 percent year-over-year growth.

The report also found that social media advertising was able to recover from some of the decline seen in 2020 at the start of the pandemic to bring in a total of $57.7 billion last year. But companies like Facebook parent Meta and Snap are continuing to contend with revenue declines caused by Apple’s iOS privacy changes, which went into effect last year and allow users to opt out of tracking, the impact of which may not be fully seen until later this year.