"Ethnomusicologist and vocalist Mark van Tongeren offers a fascinating insight into timeless and universal aspects of the human ability to sing many tones at once. Grounded in a decades-long practical and theoretical study of music, he draws upon fieldwork and interviews with Eastern and Western musicians and composers across the spectrum from archaic traditions to contemporary experiments. This copiously illustrated book examines claims about the healing effects of overtones, juxtaposing local and global practices and transforming some of our core ideas about sound and music. An indispensable guide for musicians, listeners and scholars seeking a deeper understanding of the nature of the human voice and its harmonic possibilities"--Back cover.