How do the different tone pitches of the Hang Gudu come about? In another video I already mentioned that the pitch of the bass pulse, generated by vibrating air, doesn’t depend on the place where it is excited or how it is excited. It depends only on the positon of the player’s hands above and in the Gu opening.
In the video we will approach this subject with four hands-on experiments. What can the observations tell us which can be comprehended by everyone who is moving his hands above and inside the Gu opening?
I considered how these observations could be illustrated and came up with the following representation. The blue mushroom-shaped cloud in the figure I call the Gu field.
The Gu field describes a space above and inside the Hang Gudu which is sensitive for pitch change.
The intensity of the blue colour shows how strong the instrument responds with a pitch change, when the player’s hand is changing its position at this point.
In order to play two adjacent tones of a scale we need very small hand movements in the center of the Gu field (the dark blue area in the figure). The more we move away from the center the bigger the needed movements are. In a certain distance hand movements no longer affect the pitch.
The most important insight I have drawn from my experiments with the Gu field is the following:
The Hang Gudu does not only consist of the vessel enclosed by the Pang sheet metal. The Gu field is also an invisible part of the instrument located partly outside of the vessel.
This should make immediate sense for those who feel the vibration of the air on the palm of their hand when it is slowly submerged into the Gu field. A lot is happening in this air space above the instrument. And as our hands are always located in or nearby the Gu field when playing the Hang Gudu, each gesture or position change can affect the pitch.