THE THROAT
SINGERS OF TUVA
Testing the limits of vocal ingenuity, throat-singers can create
sounds unlike anything in ordinary speech and song
— carrying two musical lines simultaneously, say, or harmonizing with a waterfall
by Theodore C. Levin and Michael E. Edgerton
http://www.uvm.edu/~outreach/ThroatSingingArticle.pdf
TRAN QUANG HAI's world throat singing 