Hi Birgit Marita, thanks for the introduction of these musicians. I haven't heard them before but i explored YouTube and found a performane where one of this vocal group plays a jaw harp ... really cool guys from Latvian.
"Freude schöner Götterfunken" (Ode to Joy) in overtone singing style by Wolfgang Saus.
More information: http://www.oberton.org
What you see in this amazing dynamic MRI (MRT) is the tongue movement building up double resonances along the melody…