CICADA

Modeling the Sound Production of the Cicada for a New Musical Instrument.
 
 

The musical potential of sounds produced in our natural environment has long been recognized. In the 17th century, Galileo wrote a parable with this very premise. In it, he described a boy who was so fascinated by the various sounds that surrounded him, he designed musical instruments to mimic them. Each time he heard a new sound, he set out to understand how it was produced so he could duplicate it. Sometimes successful in his endeavor, and sometimes not, he always had an abundance of new sounds to explore.

Now, in the 21st century, we have a similar goal, and with physical modeling technology, there is much greater potential for achieving it. Though a large part of the field is currently devoted to understanding and duplicating existing traditional instruments, I propose that the technology can be just as useful for creating new ones. While increasing the musicians repertoire of musical instruments, it also allows the user to intuitively manipulate acoustical phenomena beyond what may be possible in the real world.

The first part of this project explores the sound mechanism of the cicada (an insect known for producing extremely loud sounds, in spite of its small body). The cicada is equipped with two vibrating plates (functioning as a mechanical resonators) called tymbals. Located on either side of the insect's abdomen, the tymbals provide a series of clicks that excite and sustain the resonant frequencies of the abdominal air sac (which acts much like a Helmholtz resonator). The sound which reaches our ears, is propagated through two sonic apertures in the abdomen called the tympanum (or the eardrums).

The current implementation uses a chirping biquad to model the main resonant frequency of the tymbal plate and a second biquad to model an additional resonant mode (approximately twice that of the fundamental). This resonator is coupled to a model of a Helmholtz resonator, tuned to the resonant frequency of the tymbal. A pair of glove controllers, equipped with force sensing resistors (FSRs) at the finger tips, allow for fine tuning of parameters such as stiffness, mass, and the quality-factor (Q), all of which contribute to the resonant frequency of the tymbal.