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.

It is thought that the art of overtone singing originated in southwestern Mongolia (modern Khovd Province and Govi Altai region). Overtone singing can be found throughout the country and Mongolia is often considered the world's most active area. The most commonly practiced style, (Cyrillic: хөөмий), comes in these varieties:

Mongolians also have many other singing styles, such as karkhiraa (literally, "growling") and isgeree.

Tuvan overtone singing is practiced in the Republic of Tuva (southern Siberia, Russia).

The Tuvan method of singing overtones is based on appreciation of complex sounds with multiple layers or textures. Tuvans have developed a wide range of rhythmic and melodic styles. Most are sung with korekteer (literally, "with chest voice"). Styles include:

Other sub-styles include: