From the Wall Street Journal:

Next time you listen to a Bob Marley channel on Pandora Media Inc., the Internet radio service may peg you as likely to vote for a Democrat.

The Oakland, Calif., company plans to roll out a new advertising service next week that would enable candidates and political organizations to target the majority of its 73 million active monthly Pandora listeners based on its sense of their political leanings.

How can it do this? The company matches election results with subscribers’ musical preferences by ZIP Code. Then, it labels individual users based on their musical tastes and whether those artists are more frequently listened to in Democratic or Republican areas. Users don’t divulge their political affiliations when they sign up for Pandora. (Take a quiz to see what your playlist says about you.)

Pandora’s effort to pinpoint voter preferences highlights how digital media companies are finding new ways to tap information that users share freely to target advertising. These go beyond the traditional tracking of Web-browsing habits. Pandora, locked in a battle for advertising revenue with Internet radio services such as Spotify, sees political advertising as a way to boost revenue.

You can read more on this story at Wall Street Journal.