Overtone singing

Overtone singing, also known as overtone chanting, harmonic singing, polyphonic overtone singing, or diphonic singing, is a singing technique in which the vocalist produces two distinct pitches at the same time. From a fundamental pitch made by a human voice, harmonic overtones can be selectively amplified through manipulating the dimensions and the shape of the resonant cavities of the mouth and the pharynx. Overtone singing should not be confused with throat singing, although many throat singing techniques include overtone singing. While overtone singing involves careful manipulation of the vocal tract, throat singing mostly involves the voice source.