Small Wings, Loud Songs

Crickets and bush-crickets use their wings to produce a wide range of often impressively loud courtship songs to attract distant mating partners. These communication signals are different for each species and highly variable in rhythm (the temporal structure) and pitch. Many species also produce like bats ultrasonic songs far beyond the human hearing range. Generally, songs are produced by rubbing a hardened edge on one forewing against a row of fine teeth on the underside of the opposite forewing, a process called stridulation. The vibrations produced during stridulation are amplified by specialized structures within the wing surface that are, like the body of a violin or guitar, adapted to resonate at the specific song frequencies. The wings have evolved in time to be small, lightweight and optimised resonators, therefore equipping these small insects with their own miniaturised, natural loudspeakers. When observing singing crickets and bush-crickets, one question springs to mind: How can these insects, using only their small wings, produce such loud songs? Or, more specifically: which morphological structures, biomechanical processes and material properties influence and ultimately define the acoustic properties the tuning of the sound producing wings in crickets and bush-crickets? To answer these questions, state-of-the-art bioacoustic and biomechanical methods (including lasers for the detection of minute surface vibrations, artificial intelligence for detailed wing motion analysis and nanomechanical exploration of material properties) will be used to study how the structure of a wing relates to the songs it produces. Knowledge gained during the project will be used to create three- dimensional and mathematical wing models based on real-life insect wings that will allow to simulate the stridulation process and the songs thereby created. Artificial manipulation of these computational models and their corresponding acoustic output will help to gain further knowledge of the mechanical potential and constraints within these miniature loudspeakers. Combining the study of real-life insect wings with the mechanical and acoustic insights gained from the virtual models has the implicit potential to help biologists to understand the processes shaping the acoustic evolution of insects and to guide engineers in the development of innovative, biomimetic miniature loudspeakers for, e.g. hearing aids.