A Musical Controller Based on the Cicada’s Efficient Buckling Mechanism

The cicada uses a rapid sequence of buckling ribs to initiate and sustain vibrations in its tymbal plate (the primary mechanical resonator in the cicada’s sound production system). The tymbalimba, a music controller based on this same mechanism, has a row of 4 convex aluminum ribs (as on the cicada’s tymbal) arranged much like the keys on a calimba. Each rib is spring loaded and capable of snapping down into a V-shape (a motion referred to as buckling), under the downward force of the user’s finger. This displacement of the rib during buckling is measured by a sensor and then passed through a differentiating circuit to get velocity. The velocity is then converted to energy and then used as the input to a synthesis model — a physical model of the acoustic elements in the cicada’s sound production mechanism. INTRODUCTION Though many bioacoustic systems are similar to those found in musical acoustics [?], the cicada’s use of a sequence of rapidly buckling ribs to excite and sustain tones is rather unique. Neither the buckling mechanism itself, nor the use of discrete impulses to sustain musical tones, seem to be used by any traditional musical instruments. Musical instruments generally require the player to supply continuous energy to sustain a tone, as in the continuous motion of the arm while bowing a string instrument, or the continuous blowing required to sustain a note on a wind instrument. Discrete excitations mechanisms such as plucking or striking generally produce tones that decay after a period of time. In this research, a music controller based on the cicada’s buckling mechanism was developed so that its potential as a musical instrument can be explored. It provides a mechanical user interface to an already existing synthesis model of the cicada’s sound production mechanism [?, ?], allowing the user to manipulate the computer model’s parameters in a meaningful and intuitive way. This paper will briefly review the cicada’s rapid sequential buckling mechanism (which is used to excite the primary mechanical resonator of the sound production system), and discusses how this mechanism is incorporated in the development of a musical controller for an existing