Smithsonian/Folkways has released an interesting CD: Tuva: Voices From the Center of Asia [with sound clips], which open mike has already mentioned above. I have a 3-CD album titled Les Voix du Monde: Une Anthologie des Expressions Vocales (Le Chant du Monde CMX 374 1010.12), which show how expressive human voices are (Tuvan kargyraa overtone song is contained).

~Masato