Expanding its move into offline media, Google will begin a public test of Google Audio Ads by the end of the year, company spokesman Michael Mayzel said this week.

Advertisers will be able to sign up for contextually targeted radio ads using AdWords, and in the meantime Google is spending heavily to expand its position in the industry, writes Reuters. "Google is…hiring sales people to sell radio…paying about 50 percent more than a typical radio sales person might make," Bill Figenshu, COO of Softwave Media Exchange, is quoted as saying.

Google is rumored to be in talks to buy about $1 billion in radio advertising inventory from Clear Channel Communications, Figenshu added. Other industry sources said Google had been approaching all radio operators. "It seems like a good time to be doing this because business is so slow. There's a lot of inventory," according to one industry exec.

Google CEO Eric Schmidt has said Google's radio effort would grow to include 1,000 employees in ad sales, engineering and operations; in January it acquired dMarc Broadcasting and its automated advertising system for radio.