particulary Xi for flûte, http://james-ingram-act-two.de/stockhausen/Xi/sxia1l.html
I just noticed the parts in IPA (phonetic alphabet). [y] [Þ] [Å]
First time I see those on a score. Interesting.
not that new, has been around since the 60s. for the few composers that
work with that and not with language text.