• by Mark Walsh  @markfwal, April 3, 2012

Online radio is the fastest growing music-listening category among U.S. consumers, according to NPD Group. The consumer research firm found 43% of U.S. Web users in 2011 chose to listen to music via Pandora, Slacker, Yahoo Music, and other online radio offerings, up nine percentage points from 2010. At the same time, music-listening on AM/FM radio and CDs stayed relatively steady, at 84% and 74%, respectively.

NPD’s annual music study found the number online radio listeners grew by 18 million last year. Listening to free online radio is most popular among young adults age 18 to 25, with strong growth seen in the 36- to 50-year-old age segment.

While demand for free online radio is increasing, the appetite for paid options remains low. Some 42% of Web users listened to free radio in 2011 compared to just 3% who paid for online radio. The research also suggested Facebook doesn’t play an influential role in Web music.

Only 12% of Web users listened to music integrated into Facebook or other social networks by services like Spotify and MOG. “There’s no doubt that Facebook has helped drive music listening and discovery,” said Russ Crupnick, SVP of industry analysis at NPD. “But what is not yet clear is the platform’s importance, in terms of ongoing music usage and purchasing.”

The study’s findings were based on online surveys of 5,799 U.S. consumers age 13 and up, between December 14, 2011 and January 3, 2012.