Eric Whitacre is known for his breathtaking compositions of choral work. He has published more than four-dozen pieces and recorded several albums. More recently, he’s become known as the guy who puts together virtual choirs. What is a virtual choir, you ask. Well, his one first involved inviting 185 voices from a dozen countries to sing and record their various parts in their living rooms, door rooms, or wherever, and send them to him. Whitacre then combined all of these recordings into a single “virtual choir.” The finished piece became an instant You-Tube sensation in 2010. A year later, he gathered more than 2000 voices from 85...