How does the clarinet change pitch?
In fact you can change the pitch by nearly one full key by
changing the pressure you blow with. Yet when you play a didj you
do not want to be forced to play it really soft or really hard just
to be in tune. It obviously limits what you can do while
playing.
In a well tuned didj the difference caused by changing the
pressure is evenly spaced on both sides of the middle note. We
actually tune so middle note is closer towards the high end as most
good players tend to use rather more pressure. This means that when
a beginner plays that didj, it will be under tuned, but once he
becomes more proficient he will be able to play it in tune.
The positioning of the lips can affect the tune as well, but I
found that this effect is small and that you have to compromise
ease of play in order to change the pitch. The tune can also be
affected by the shape and height of the beeswax mouthpiece. In
general, the larger the hole in the mouthpiece, the further your
lips will go into the didj, resulting in a higher pitch. And the
higher the mouth piece the lower the pitch.