Lesson proposed by TRAN QUANG HAI for learning throat singing, part 2, FRANCE, 2009 16.02.2018 by Hai Tran Quang Lesson proposed by TRAN QUANG HAI for learning throat singing, part 2, FRANCE, 2009 QuangHai Tran Ajoutée le 22 févr. 2009 Trân Quang Hai proposed his exercice with double mouth cavity concerning the production of overtones .