SM: Your book, "Healing Sounds: The Power Of Harmonics" focuses on sound healing, but it explores a fascinating aspect of the human voice, the ability to create two or more notes simultaneously.

JG: Yes, this is called "vocal Harmonics" or "multiple overtones." It is a very powerful and ancient esoteric technique that has been employed in various shamanic and spiritual traditions, including Mongolian shamanism and Tibetan Buddhism. It also has been used in various magical schools that probably date back to ancient Egypt, if not before.

SM:  What exactly are harmonics?

JG:  Harmonics, or overtones, are a phenomenon of sound that occurs whenever sound is created. All sounds that are produced are not single tones, but mixtures of pure tone frequencies or harmonics. There is a fundamental tone as well as overtones which make up the spectrum of sound. These harmonics are geometric multiples of the fundamental, meaning that if the fundamental frequency is 100 cycles per second, and the next overtone vibrates twice as fast, at 200 cycles per second, and the next overtone vibrates 3 times as fast, at 300 cycles per second and so on. Harmonics are responsible for the tone color or the timbre of different instruments and our voices. Just as you can hold a prism to white light and refract the different colors of the rainbow, it is possible to learn how to use your voice to break up these harmonics into specific sound frequencies.

SM: Your book examines the use of harmonics in shamanic and spiritual traditions, as well as in their application in scientific and medical arenas. What is so special about these "vocal harmonics"?

JG:   From a spiritual aspect, harmonics may resonate different etheric centers and subtle bodies and fields and invoke specific deities and energy forms. From a more scientific and physiological viewpoint, harmonics seem to be frequencies that affect the nervous system and the brain. As Dr. Alfred Tomatis, M.D., indicates, high frequency sounds may actually charge the brain. They are extraordinary tools for relaxation and may hold a major key to the use of sound for healing and transformation.