Credit: copyright '01-'06 Dale A. Clark
Kiva teaches this vocal technique, which allows a single voice to produce two or more pitches simultaneously. The lowest pitch is the fundamental, from which corresponding harmonics are emphasized and controlled through a series of vowels and shaping of resonant cavities. Known by various names (i.e. harmonic chant, Mongolian overtone chant, polyphonic singing), it has developed over three decades in the west, inspired by throat singers of central Asia (mainly Tuva, Mongolia and Tibet). Western overtoning and throat singing are quite distinct from one another. Tuvan throat singing has several techniques and sub-styles. This has been popularized by the group Huun-Huur-Tu since the early 90's. Another distinct form of throat singing is practiced by Canada's Inuit people.
David Hykes, is one of the earliest contemporaries who coined the term 'harmonic chant' to describe his ethereal whistle-like style in the '70's. However, a cylindrical disc recording exists from the late '20's in which an American cowboy overtones, presumably through his own invention.
Due to its relatively young status, western overtoning does not really have a tradition. In comparison, central Asian throat singing goes back at least as far as the Silk Road trade, and is widely believed to have shamanic origins. The vast majority of these Asian singers are male, although these days it is becoming more acceptable for women. There are many practitioners of overtoning in the west now. It can be found lurking in the background of practically any genre you can imagine, from New Age to jazz to world to pop, etc. Since the doors are wide open to its usage, experimentation is rampant. It is not gender specific. Apart from musical applications, it is also used for meditation and sound healing purposes.