has continued its push into traditional media with a beta launch of its radio advertising system in the US.

The search giant said it had begun testing the Audio Ads service with 20 AdWords customers and over 700 radio stations, having reworked the technology of dMarc Broadcasting, the radio advertising company it bought almost a year ago.

“We’re happy to announce that the integration is now complete and we’ve recently begun a US beta test of Google Audio Ads with a small group of AdWords advertisers,” Google said in a statement.

The Audio Ads service allows marketers to use Google’s AdWords system to book ads with radio broadcasters. When they access AdWords, advertisers are given an option to bid for slots and to target their ads to various categories.

The company is also testing a service that helps advertisers that are new to the medium to create radio ads.

Last month, Google launched trials of its Print Ads service, which extends AdWords-style buying to newspaper and magazine advertising. It hasn’t said when either service will be publicly launched or offered outside the US.