The harmonic-dominant signals in animal communication involve the use of new resonant frequencies

Acoustic signals in animals are classically produced using source-filter mechanisms. Many species are capable of producing high-frequency sounds characterised by dominant harmonic frequencies. These signals emerged following an evolutionary phenomenon known as "harmonic-hopping". The study of the source-filter mechanism of Eneopterinae crickets suggests that emergence of harmonic-dominant signals is linked to changes in the physical properties of the filter. To test this hypothesis, we used laser Doppler vibrometry and finite element modelling to characterise the vibro-acoustic behaviour of the sound-producing forewings of two species of Eneopterinae crickets. Our results suggest that the forewing venation plays a key constraining role distinguishing the two species' respective vibro-acoustic behaviours. Our results also highlight the role of the membrane deformation and the damping properties of the forewings in the sound-producing mechanism of these crickets. We suggest that harmonic-hopping may be associated with the emergence of new resonant frequencies in the forewings of Eneopterinae crickets.