Google has released more info on their plans on the AdWords Blog.
Google Audio Ads brings efficiency, accountability, and enhanced ROI to radio advertising by providing advertisers with an online interface for creating and launching radio campaigns. You’ll be able to target your customers by location, station type, day of the week, and time of day. After the radio ads are run, you will be able to view online reports that tell you exactly when your ad played.
Over the last year, we’ve been partnering with both terrestrial and satellite radio stations across the U.S. so that our advertisers have many options for broadcasting their ads — whether it’s a Country station in Tyler, Texas or an Adult Contemporary station in New York City. Currently, there are hundreds of stations to choose from and we hope to grow the list over the coming year. Our broadcast partners are looking forward to making their ad inventories available to thousands of new advertisers, especially since they aren’t easily accessible today.