Clear Channel, the largest radio station owner in the United States, has teamed up with music intelligence platform The Echo Nest to build an Internet radio service similar to Pandora and Last.fm.

Clear Channel's iHeartRadio service uses The Echo Nest's massive dataset of 30 million songs and 5 billion related data points to let users create radio stations based on their musical tastes. It has been dubbed a potential "Pandora killer" by Billboard and indeed its functionality could hardly be more similar to Pandora's. Users can create stations based on a particular artist or song, vote tracks up or down and skip a limited number of songs per station.

The service packages a personalized Internet radio streaming experience alongside a large directory of Clear Channel's pre-programmed radio stations, which can be streamed for free.

With this launch, Clear Channel is clearly taking a shot at Pandora and similar Internet radio products. Even though traditional radio broadcast stations still make up the lion's share of total listenership, online streaming services have been growing fast, with the newly-public Pandora posting some promising early financial results.

In testing out iHeartRadio, we found it to be a pretty solid service overall. Some of its recommendations were a little predictable, and we found that the song-to-song matches sounded more like matches based on artist. For example, we started a station based on a slow, more ambient-sounding song by Radiohead and the songs that played were just random songs by artists commonly associated with Radiohead, including some up-tempo rock songs that sounded nothing like the original track.

Still, the potential advantage that The Echo Nest's recommendation engine offers is in the size of its dataset. With 5 billion datapoints and 30 million songs indexed, it just might pose a credible threat to Pandora's 800,000-song index. The Echo Nest uses acoustic analysis, data-mining, natural language processing and machine learning to listen to and learn about music, including the relationships between various songs and artists. It currently powers just under 200 Web-based music apps, including from some big players like MTV, the BBC and MOG. It also powers scrappy, but neat independent Web apps like Echofi, the Spotify recommendation tool we wrote about yesterday.

iHeartRadio is in open beta. To try it out you'll have to connect your Facebook account and 'Like' the product on Facebook (yes, before trying it and determining if you actually like it or not). In addition to a Web interface, the service has mobile apps for iOS, Android, Blackberry and Windows Phone 7.

Lead photo by Andrew Taylor.