Rollin Rachele is one of the world's foremost overtone singers and the author of the acclaimed Overtone Singing Study Guide. Overtone Singing is a mesmerizing technique where one person sings two notes simultaneously. The second note perceived sounds like a flute or a synthesizer, but what you are hearing is the human voice. Overtone singing, or throat singing as many know it, is most widely recognized in Tuvan, Mongolian and Tibetan cultures. It is a widely held belief that overtone singing has it's roots in such folk traditions, yet this is a misconception. Overtones are the building blocks of all sound and are present in all musical traditions and forms. Rollin has used his scientific knowledge of the harmonic series and his artistic talent to create a western, classical form of overtone singing. His sound is softer, sweeter and purer than the traditional Xhoomii technique. With this, he takes the experience of throat singing on to another musical dimension for his listeners and students. Originally from Oregon, USA, he has been living in Europe since the 1980s. For the past 25 years Rollin has been working internationally, developing, performing and teaching overtone singing in a variety of settings including universities, music schools, festivals, and places as diverse as The Lincoln Centre and The Esalen Institute in America to the yurts of Mongolia. He was introduced to overtones, when a Men's Choir at Oregon State University in 1979 played an ethnomusicologial recording of the Mongolians Xhoomii. During the following years this became his main focus. He has been teaching and performing overtone singing world-wide since 1983. In 1991 he began studying Indian Classical singing with Ustad Mohammad Sayeed Khan and has been combining and using elements of both disciplines in his performances. Based on his musical fusions that span many different cultures, Rollin's music falls into the category of world music. Some of the other forms of music that Rollin has performed throughout his professional career are Barbershop, Vocal Jazz, Musical theatre, Gregorian Chant, Medieval, Polyphonic Music. He also conducted several choirs in The Netherlands over the years. He has been a guest lecturer internationally at many prestigious universities including Princeton, SOAS, CalArts, Oregon State University and Conservatories of music in Amsterdam, Utrecht, Rotterdam, He has also performed and lectured at the annual American Laryngological Voice Research and Education Foundation meetings in Philadelphia. He has also instructed performers such as Mark von Tongeren, Michael Ormiston and Tim Wheater. He is currently working on a project called 'Sufi Connect' with performer Raja Mushtaq. This world music compilation will blend the sacred sounds of Qawwali, Indian ragas and overtone singing. In addition to Harmonic Divergence he has also authored The Overtone Singing Guide with exercise CD, which was completed in 1996, he also has 2 other CDs featuring overtones: Sound Reflections and Whistling Pastimes. He is also Director of Creativity and Innovation of Abundant Sun Ltd. Abundant Sun is an educational consultancy based in the United Kingdom that provides training in: business ethics; creativity and innovation; corporate responsibility; complexity science; and global diversity.