AI media buying tests are expanding to audio. Rochester, N.Y.-based independent media agency Butler/Till and iHeartMedia have been testing the use of AI media buying agents on streaming audio and podcast inventory, Digiday has learned. The two companies piloted an agentic buying solution for a four-week campaign running between July and August, on behalf of a U.S. client in the agricultural sector that Butler/Till declined to identify. The syste…