Have you ever had a fast passage in a piece of music and your fingers and tongue were running circles around each other but never lining up?
Cue double tonguing!
First off what is double tonguing?
Double tonguing is when alternating back and forth on two different parts of your tongue to articulate. The tongue will hit just behind your front teeth as well farther back on your palate. This allows your tongue to sound notes two or three times as fast as normal tonguing.
The Mechanics of Double Tonguing
Most flute players will double tongue with the syllables tu ku tu ku or du gu du gu. Both are correct (although if you tend to have a heavy tongue du gu might be a better option). Use whichever comes easiest to you and start by just whispering the sounds. March around the house to your own little double tonguing parade. Do it backwards and forwards tu ku tu ku and ku tu ku tu. Also try doing it only with the ku. Try to keep the ku or gu part of your tongue as far forward as possible in your mouth.
tip: try articulating the syllables through a smoothie straw to help you both hear the sounds and strengthen your airstream. Keep the straw in front of your teeth so you can articulate behind your teeth.
After you feel confident without your flute, add the instrument and try double tonguing on major, minor, and chromatic scales. You could also double each note in the scale (playing a tu ku on each note before moving on). Again practice tu ku and ku tu and only ku.
Daily Practice
Practice your double tonguing every day! Even just a few minutes a day will increase your ability and speed. You want your back syllable (ku or gu) to be just as strong as the front one so that no one can hear the difference between the two.
Some great pieces to practice double tonguing on are:
Scales (beginning to advanced)
Etudes (beginning to advanced)
Bach Sonata IV Allegro (intermediate to advanced)
George Enescu Cantible et Presto (intermediate to advanced)
"Voliere" orchestral excerpt from Carnival of the Animals (advanced)
William Tell overture orchestral excerpt (advanced)
A Midsummer Night's Dream orchestral excerpt (advanced)
Whatever piece you are working on (beginning to advanced)
After you master double tonguing you will never want to go back (well maybe sometimes).
Now on to triple tonguing....!
That's a lesson for another time.