The Upper Register of the Oboe

One of the ways of achieving the upper register of the oboe is opening a hole in the side of the air column close to the mouthpiece. Opening a hole releases excess air pressure and destroys the fundamental vibrational mode. If properly positioned, the hole favors the second harmonic mode which has a pressure node (displacement antinode) in the region near the mouthpiece.

Lower register

Upper register

One of the mechanisms for register change is a key with a hole in it which is kept covered with a finger of the left hand when playing notes in the lower register. The upper register can be achieved by lifting the finger from this hole as demonstrated above.