``Tonguing''

In reply to a Flute Forum comment asking what is ``double tonguing'':

Assuming you're not trolling...

Single tonguing uses only the tip of the tongue with either the "T" or "D" consonant sound + harmonic-specific vowel as articulation. So if you see people say things like "Tee Tee Tee" or "Duu Duu Duu", it's single tonguing.

Double tonguing uses the tip of the tongue and the base of the tongue in a coordinated way to produce articulations that are double the speed of single tongued articulations. The tip of the tongue is still "T" or "D" consonant sound + harmonic-specific vowel, while the base of the tongue uses "K" or "G" consonant sound + harmonic-specific vowel. So if you see people say things like "Tee Kee Tee Kee", or "Duu Guu Duu Guu", it's double tonguing.

Triple tonguing is double tonguing, but for faster rhythms. The main use of triple tonguing is for handling triplets -- you'll often see people say "Tee Kee Tee; Kee Tee Kee", "Tee Kee Tee; Tee Kee Tee", "Duu Guu Duu; Guu Duu Guu" or even "Duu Guu Duu; Duu Guu Duu". In other circles, the rhythmic pattern of quaver-double-semi-quaver may also be referred to as triple tonguing ("Tee <breathe> Tee Kee", "Duu <breathe> Duu Guu").

Of course it is a bit more detailed than that, especially the part on the ``harmonic-specific vowel''. The details may be found at my dizi article explaining the matter.