Nature of nonlinear mechanisms in the generation and propagation of sound in the cicada mating call

Abstract

Experiments and analyses (Hughes et al., JASA, 2009) on the relationship of body surface displacements with external acoustic pressure measurements while cicadas are generating mating calls resulted in the conclusion that the relationship is substantially nonlinear. The present analysis assesses whether the propagation through the air is nonlinear propagation. Suspicion that such might be the case is suggested by the fact that the sound levels at 90dB within less than a meter of the sounding cicada. Computational results reported in the present paper indicate that nonlinear effects are likely to occur very near the body surface. A suggested explanation is based on the observation that the displacement of the body surface varies with position over the surface. The time history of displacements at different points along the body surface is not as repetitive during successive tone burst generations as is the total volume displacement of the surface. This is consistent with the observation that buckling of the long ribs in the tymbals may be the ultimate cause of the surface displacement vibrations. © 2013 Acoustical Society of America.