Overtone singing:
taken from the FAQ of Friends of Tuva website:
http://www.fotuva.org/faq/part_1.html
Khoomei is easiest for men. I *have* heard a recording of a Mongolian Kazakh women singing khoomei, but it's simply not so easy or spectacular, because of the higher pitch of the female voice. (Sainkho Namchylak can sing khoomei too.)
1. Sing a steady note while saying "aah" (to start with). Pitch it in the middle of your range, where you can give it plenty of energy, i.e. - Sing it loudly.
2. Aim to make the sound as bright - not to say *brash* - as you can. The more energy there is in the harmonics, the louder and clearer they'll be when you start singing khoomei. Practise this for a while.
3. OK, with this as a basis for the sound generation, you've got to arrange your mouth to become a highly resonant acoustic filter. My style (self-taught, but verified for me by a professional Mongolian khoomei singer I had a lesson with in Ulaanbaatar) is as follows:
Divide the mouth into two similar-sized compartments by raising your tongue so that it meets the roof of your mouth, a bit like you're saying "L". Spread your tongue a bit so that it makes a seal all the way round. At this point, you won't be able to pass air through your mouth. Then (my technique), break the seal on the left (or right) side of the mouth, simply to provide a route for the air to get through.
Then (here's the most difficult bit to describe over the net - or even in person, for that matter!), push your lips forward a bit, and by carefully (and intuitively) adjusting the position of your lips, tongue, cheeks, jaw, etc, you can sing Mongolian khoomei!
Put it this way: the *aim* of the khoomei singer ("khoomigch") is to emphasize ONE of the harmonics which are already present in the sound generated by the throat. This is achieved because he is forming a resonant cavity, which (a) is tuned to the chosen harmonic (overtone), and (b) has a high resonance, or "Q" factor. By adjusting the geometry and tension of your mouth you can choose which harmonic you're emphasizing, and thus sing a tune.