The folks at ZDNet’s Digital Markets have some PowerPoint slides that illustrates how Google Audio Ads work. And this from Voices.com:

“Google has positioned the Audio Ads system to serve both top-level advertisers, as well as the advertising agencies themselves. The graphic also shows 75% of the transactions coming from the agencies, and only 25% from independent advertisers. This is likely because advertising agencies already have media planning and media buying personnel, not to mention existing relationships with local and regional radio stations.”

The lables in the little blue rectangles are: Radio Stations, Networks and Rep Firms. Which suggests that advertisers will simply have another option for placing their ads on radio stations. And if Google can make it easier or cheaper or more effective (i.e. feedback, reports, etc)… they’ve added value to the process.