Yahoo Inc. has begun testing a new search engine feature that could help educators and students find audio files from the internet for use in lesson plans, class projects, and personal use. The free service boasts an index of more than 50 million audio files, including newscasts, speeches, and interviews posted online, as well as the internet’s deepening pool of “podcasts”–recordings made to be played on a computer or digital device such as Apple Computer’s iPod player. Other internet search engines, such as America Online’s Singing Fish and Blinkx, already find audio files, but Yahoo is touting its service as the most comprehensive, largely because it has received permission to index downloadable songs offered by virtually all of the internet’s top music services. “It’s really one-stop shopping for the music fan,” said Bradley Horowitz, Yahoo’s director of technology development, search, and marketplace group. Yahoo’s expansion into audio search coincides with an increasing emphasis by Yahoo and other top search engines on indexing online video. The diversification beyond searching simple text online reflects the web’s evolution into a multimedia hub–a shift the top search engines hope to parlay into profits. Yahoo won’t display ads next to its audio search results initially, but that could change as the service evolves, Horowitz said. Google Inc., the internet’s search engine leader, does not yet have its own audio feature. (Material from the Associated Press was used in this report.)