Nonlinear acoustics in cicada mating calls enhance sound propagation

Area of Science:

• Bioacoustics
• Insect acoustics
• Nonlinear acoustics

Background:

• Cicadas are known for producing some of the loudest sounds in the insect world relative to their small size.
• The sound production system of cicadas, utilizing tymbals and a resonant abdomen, is surprisingly efficient.
• Linear acoustic models fail to fully explain the high sound energy radiated by cicadas.

Purpose of the Study:

• To investigate the acoustic characteristics of cicada mating calls.
• To determine the primary factors contributing to the high sound energy radiated by cicadas.
• To explore the potential applications of cicada sound production principles in technology.

Main Methods:

• Field experiments measuring cicada mating calls.
• Analysis using mutual information and surrogate data techniques to identify nonlinear behavior.
• Application of the Volterra expansion technique to model the nonlinear signal characteristics.

Main Results:

• Cicada mating calls exhibit significant nonlinear characteristics.
• The nonlinear nature of the signal is a primary contributor to the high acoustic energy radiated.
• The medium appears to play a role in the efficient propagation of cicada sounds.
• Second-order Volterra estimates confirm the dominance of nonlinear features in cicada calls.

Conclusions:

• The loudness of cicada mating calls is largely due to nonlinear signal dynamics.
• Understanding these nonlinearities offers insights into efficient sound propagation.
• Principles derived from cicada acoustics may improve sonar system performance.