AI agents enter audio ad buying: inside the Butler/Till and iHeartMedia test

Independent media agency Butler/Till and audio giant iHeartMedia have extended agentic media buying — letting AI agents set up campaigns and purchase inventory automatically — into audio, covering streaming audio and podcast inventory. In a four-week pilot run across July and August, two AI agents, one built by Butler/Till and one by iHeartMedia, were connected through an MCP server: a human planner handed the campaign brief to the agency's agent, which passed it along to the publisher's agent.

Two things set this test apart from earlier attempts. It is the first to cover audio inventory, and the transaction ran directly between agency and publisher, with no intermediary such as SSP Pubmatic in the middle. According to Christy Murphy, associate director of programmatic at Butler/Till, the results were significant: the campaign's CPM came in 42% below the client's usual benchmark for traditional buying, while 48% of podcast impressions landed in the most valuable, non-skippable ad slots — compared with roughly 33% under a conventional plan.

iHeartMedia chief business officer Lisa Coffey frames the experiment as a way for audio to claim a larger share of the digital advertising ecosystem, which currently sends just 3.95% of global ad spend its way. eMarketer analyst Ross Benes is more cautious, noting that only about a third of digital audio volume is sold programmatically, against nearly 90% for digital advertising overall — which keeps the reach of agent-led buying limited for now.

Beyond Butler/Till, WPP Media is building an agent for video inventory and Omnicom is working along similar lines, a sign that agentic buying could narrow the capability gap between the big holding companies and independent shops. "It gives us an edge in how our people work — the agents handle speed, flexibility and campaign execution, and we put more of our energy into strategy," Murphy says.