I learned of Hai’s work on overtone singing in the early 1990s. When I got to know him personally, I was astounded and (I will admit) a bit intimidated by his unbridled energy. He loves to share what he does, and he is in fact overflowing with enthusiasm: for overtone singing, for Vietnamese music, for playing the Jew’s harp and spoons, for ethnomusicology, for his constant travels as a performer and teacher
The most prolific researcher in the field of overtone singing is a man with many faces. His name is Tran Quang Hai and you can call him (and all options are correct): Vietnamese or French; a professional musician or a professional musicologist; an instrumentalist or a singer; an improviser or a composer; a traditional, a popular or an experimental musician (all three will do); an expert in Vietnamese traditional musics and an astute chronicler of its year-to-year development in the past decades
Mark Van Tongeren in his article “MARK VAN TONGEREN: Catching up with Tran Quang Hai”, 2019
TRAN QUANG HAI's world throat singing 