American composer Eric Whitacre’s virtual choir has united singers from around the world.

The musical revolution will be streamed online… In May 2009, American composer and conductor Eric Whitacre was sent the link to a video posted on YouTube by Britlin Losee of Long Island, New York. The young singer had recorded the first soprano part of his work Sleep. While the video won’t win any awards for filmmaking, Losee’s rapt performance of her soaring part, isolated from the rest of the choir, is haunting. On seeing the video, says Whitacre, an idea hit him “like a brick”. “I was struck so hard by the beauty of it, the intimacy of it, the sweetness of it.” He wondered what would happen if more people recorded a part: if you combined them, would it result in a satisfying musical experience? Whitacre called for submissions via his blog, combined the results and discovered that it actually sounded like music.

 In the next phase of the experiment, Whitacre pushed for more musicality, posting a video of himself conducting his a cappella piece Lux Aurumque on YouTube and making the vocal parts available for download. Harnessing the power of Facebook and his...