Google has announced that it has signed a multi-year agreement that enables the search engine to sell a guaranteed portion of 30-second advertising inventory available on more than 675 of Clear Channel's AM/FM stations.

Under the agreement, Google Audio Ads advertisers will have national distribution in America, enabling them to reach specific audiences, at specific times, in targeted geographies.

"This is a true win-win", said John Hogan, Chief Executive Officer of Clear Channel Radio. "Clear Channel Radio gets access to an entirely new group of advertisers within a new and complementary sales channel, and Google adds another option for its existing customers. Google has proven its ability to gain premiums for advertising inventory and that fits perfectly into our broader strategy of building value for advertisers while increasing our overall revenue yield."

On Friday, Google announced that it had paid $3 billion for advertising company DoubleClick.