in german we call it: “oberton singen” (overton singing?)
http://de.wikipedia.org/wiki/Oberton
and: of course: jodeln (jodel)
http://de.wikipedia.org/wiki/Jodeln
a other example for “oberton” without jodel:
http://ikbis.com/rebell/shot/30540
cool!
what do they call this kind of art?