Subscription music service Rdio plans to create an ad-supported free music service as part of a new partnership with radio broadcaster Cumulus Media that could help it keep pace with Spotify and other competitors. The deal is expected to be announced on Monday, according to The New York Times , which first reported the news. As part of the agreement, Cumulus, which owns more than 500 radio stations, will take a “significant equity” stake in Rdio’s parent company, and in exchange will sell advertising for Rdio’s new free service, the Times reported. Cumulus will also give Rdio “broad access to its programming,” as well as “promote Rdio on its stations.” Cumulus’ interest in Rdio is to help expand the broadcaster’s online presence. “This..