The overtone singing

Overtone singing is a special vocal technique
allowing one person to sing 2 simultaneous sounds : a low
sound named “fundamental” or “drone” and a more high-pitched
sound called “harmonic”.

This remarkable vocal art is based on an universal physical principle : the
harmonic series. To simplify matters, let's consider that all musical sound
is made up of a fundamental vibration and a spectrum made of harmonics of
which the frequencies are whole multiples of the frequency of the fundamental.

Generally these harmonics are not individually heard but they amalgamate
to create the tone.

For example, the 12
first harmonics of C

Note : Most of the pitches of these harmonics do not correspond exactly
to the pitches of the notes of our western musical system (equal temperament).

The technique of overtone singing consists in using the oral cavity as a resonant chamber to reinforce
a harmonic which then appears as an independent pitch, superimposed on the fundamental sound.

The overtone singing is an integral part of the musical life in Mongolia and Tuva. As an ancestral vocal
practice, it is traditionally connected to nature and its forces. The events of daily life (imitation of wind, of
animal noises...) are governed by the rhythm of overtone singing. It is found as well in other countries such as
Tibet where the Gyuto monks use it in their spiritual practice and in South Africa in the music of Xhosa women.

This vocal art has aroused many western musicians' interest
(K. Stockhausen -Stimmung-, David Hykes, Tran Quang Haï...) since the end of the 60's.