As earlier rumored, starting today Yahoo will begin testing a music and audio search engine, the AP reports. The search will provide access to an index of more than 50 million audio files, including newscasts and podcasts. The index identifies the content by reading metadata embedded in the files.

Yahoo's move comes as the available audio content is undergoing exponential growth.

Other search engines, such as AOL's Singingfish and Blinkx, have featured audio search for a while now, but Yahoo says its is the most comprehensive because it has partnered with the top music services. Yahoo will get a commission for songs downloaded via its referrals. Its results will cull information from its own recently introduced music service to provide detailed information to searchers.

The current version of the service has no advertising, but ads might be added later, Bradley Horowitz, the company's director of media and desktop search, told the New York Times.

Search Engine Watch provides a detailed review of the available Yahoo Audio Search features.