Achroia grisella's ear as inspiration for acoustic sensing

Bio-inspiration, gathering insight from looking at nature, can be useful when trying to solve challenges innovatively. Insects are forced by their body size and the energy cost of a hearing organ to make many clever adaptations for hearing. Achroia grisella is a nocturnal moth with a hearing sense. It uses it both for avoiding predators and mating, the latter being an unconventional role among moths. The moth is capable of directionality that seems to be monoaural and dependent exclusively on morphology. We develop a model with the goal of 3D printing a structure whose behavior is similar to that of the moth ear, i.e., directionality at a low design cost. Starting from a simple circular plate model, we progressively incorporate more complex elements to improve the resemblance to the natural system. Equations, simulations, and 3D printed devices' frequency responses (measured through Laser Doppler Vibrometry) are compared. The directionality of the printed devices is analyzed.