Nonlinear Analysis of Sub-harmonics Signal in the Cicada Graptopsaltria nigrofuscata

The aim of this study involves identifying the causes of sub-harmonics in the cicada Graptopsaltria nigrofuscata. Three peaks were generated in the calling song, the scream, and during the experiment, which aimed to examine the resonance condition of the abdomen. The tymbal produced a simple vibration with just one IN- and OUT-click, and this frequency was similar to the 2nd peak. In conclusion, the dominant frequency of the sound produced by the cicada G. nigrofuscata corresponds to the 2nd peak, ranging from 5 kHz ~ 6 kHz. This occurs during IN-click of the tymbal. The 1st peak is a sub-harmonic, representing half of the dominant frequency, while the 3rd peak is a superharmonic, representing double the dominant frequency. The generation of the 1st peak was successfully interpreted as a result of nonlinear resonance.