Eric Whitacre: A virtual choir 2,000 voices strong

In a moving and madly viral video last year, composer Eric Whitacre led a virtual choir of singers from around the world. He talks through the creative challenges of making music powered by YouTube, and unveils the first 2 minutes of his new work, “Sleep,” with a video choir of 2,052. The full piece premieres April 7 (yes, on YouTube!).