I have not met Yavgaan. However here are a few of his words regarding Khöömii. More to follow..
- Höömij - (overtone singing)
performance of overtone singing takes usually place during social events such
as eating or drinking parties.
The Mongols call their overtone singing höömij (= throat, pharynx). The singer creates a constant pitched fundamental considered as a drone, and at the same time modulates the selected overtones to create a formantic melody from harmonics.
Several techniques are known, depending on the vocal source and the place of resonance: kharkhiraa = lung, khamriin = nose, tövönkhiin = throat and bagalzuuriin = pharynx. Overtone singers form and vary sound and timbre with their mouth, teeth, tongue, throat, nose and lips. They always form two distinct tones simultaneously sustaining the fundamental pitch.
Overtone singing can also be heard from Turkic-speaking tribes in disparate parts of central Asia. The Bashkir musicians from the Ural Mountains call their style of overtone singing uzlyau; the Khakass call it khai, the Altai call it koomoi and the Tuvinians khoomei.
Up to date, overtone singing is a common feature of Siberian peoples as well as the Kazakhs and Mongolian tribes. Overtone or throat singing is a special technique in which a single vocalist produces two distinct tones simultaneously. One tone is a low, sustained fundamental pitch (a kind of drone) and the second is a series of flutelike harmonics, which resonate high above this drone. Who masters this singing technique may even make the overtone sound louder then the fundamental pitch, so the drone is not audible anymore. A different technique often used by overtone singers combines a normal glottal pitch with the low frequency, pulse-like vibration known as vocal fry. The Turkic tribes in the Altai use to sing their texts in such a low vocal fry register of about 25-20 Hz).