When playing the bassoon there are vowel shapes or "voicings" that are used to get the correct pitch and tonal quality. Simply using the correct voicing along with the correct fingerings and suddenly you are telling the bassoon which pitch you want. Voicings are not actual vocal sounds but rather the shape used to get the correct tongue and embouchure placement.
These words will help you create the four main voicings:
Flatter voicings <---- pitch ----> Sharper Voicings
"Ah" as in Paw, Raw or Caw. "Ew" as in Dew or Pew
"Oe" as in Doe or Poe "Ee" as in We or Key
Use these voicings in different registers like this:
*Higher dynamics require a more open voicing while the lower dynamics usually require a more closed voicing.
Voicing Exercises
Bocal Exercise - The bocal and reed should make a Concert C when played with the proper embouchure using the "dew" pitch.
Transfer this exercise to the complete bassoon
The "Saggy" C Exercise - Play the B using the C fingering then move to the regular E natural fingering.