Description of WAHHA GO GO from Pink Tentacle:
According to the video, WAHHA GO GO is activated by spinning the torso-mounted metal disk (an optional crank arm can be used for greater speed). The disk's rotational energy is transferred to the machine's left and right arms via a gear assembly in the lower back. As the arms rotate, the accordion-like lungs expand upward, drawing in air that is then exhaled through the machine’s artificial vocal cords.
Another set of gear wheels in the spine transfers some of the spinning disk's rotational energy to the head assembly, which includes a pair of tiny arms that stretch and relax WAHHA GO GO's artificial vocal cords (thus regulating the pitch), as well as an arm connected to a valve that controls the flow of air from the lungs. This arm also opens and closes the mouth, which alters the so-called "formant characteristics" (resonant frequency) of the laugh, producing the "wa" and "ha" sounds.
By incorporating a series of mechanisms that work together to control the pitch, resonant frequency, and amount of air supplied to the artificial vocal cords, WAHHA GO GO is able to produce an uncanny human-like laugh.
Here is the original post: Video: Anatomy of WAHHA GO GO.
[ Thanks Joanne! ]