Republic of Kalmykia

Overtone singing, also known as overtone chanting, or harmonic singing, is a type of singing in which the singer manipulates the resonances (or formants) created as air travels from the lungs, past the vocal folds, and out the lips to produce a melody.

Another name for overtone singing is throat singing, but that term is also used for Inuit throat singing, which is produced differently.

Throat singer in Kalmykia: Vladimir Karuev (Okna Tsagan Zam)

The partials (fundamental and overtones) of a sound wave made by the human voice can be selectively amplified by changing the shape of the resonant cavities of the mouth, larynx and pharynx. This resonant tuning allows the singer to create apparently more than one pitch at the same time (the fundamental and a selected overtone), while in effect still generating a single fundamental frequency with his/her vocal folds.