How Musicians Convey Emotion Through Music

New research from Daniel Levitin, author of the bestseller, "Your Brain On Music," provides evidence that the subtle changes in timing and volume that musicians make when playing is the key to their ability to convey emotional content in their music.  The effect of such small variations explains why no two renditions of the same composition sound alike. We speak with Levitin about his new computer-based study that measures musical pleasure. He calls it "'Expressivity."