Songmaster
Songmaster (1980) is a science fiction book by Orson Scott Card.  The story of the Songmaster occurs in a future human empire, and follows Ansset, a young boy whose singing voice has the power of making people's feelings stronger.  This makes him both a possible healer and destroyer. He is trained in the art of singing so perfectly that his songs can show ideas and feelings better than words.  This book was based on Card's short story "Mikal's Songbird".