Web search leader Google is hiring scores of radio sales people and is spending heavily in a bid to expand its position in the $20 billion radio industry. Google spokesman Michael Mayzel said this week that the company will begin a public test of Google Audio Ads by the end of the year. Advertisers will be able to go online and sign up for targeted radio ads using the same AdWords system they use to buy Web search ads. Google is generally testing its ability to move into offline media, this week saying it would help customers buy advertisements in 50 U.S. newspapers.