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Odontocetes have developed a broadband sound reception system that performs well underwater. We used aluminum materials and soft silica gels to fabricate a bio-receptor to mimic the sound reception system of a finless porpoise. Both numerical modeling and experiments suggested that compared to omnidirectional reception, the porpoise-inspired receptor can achieve broadband and directional sound reception with frequencies ranging from 15 to 90 kHz and enhance the reception by an average of 3.9 dB in this bandwidth. At some frequencies, this reception improvement can reach 7.3 dB in experimental data. This work provides an alternate idea to design sound receptors to be applied in underwater broadband and directional sound reception. [ABSTRACT FROM AUTHOR]

Finless porpoises have evolved to equip a unique sound reception system composed of acoustic structures with gradient sound speed and density to achieve sound reception. Through numerical simulations and experiments, we demonstrated that this reception feat can be accomplished through physical implementation. Using the effective medium theory, we built respective composites to form an artificial bioinspired receptor to mimic the sound reception system of porpoise. This paper introduces an alternate aspect to bridge the gap between natural biosonar and artificial construction, shedding lights on inspiring additional advanced sound reception designs and systems. [ABSTRACT FROM AUTHOR]

We demonstrated that the feats of the dolphin biosonar system can be achieved through physical implementation. Numerical and experimental results suggested that dolphins have evolved to intelligently manipulate physical laws. Gradient distributions of sound speed and density in the forehead counterpart can enhance the main beam by gathering more sound energy to reinforce the main beam and lowering side lobes. As dolphins prove to accomplish efficient control on their biosonar capabilities in multiple ways, this paper provides an additional aspect to enrich our understanding of how one of the best natural biosonar systems works and build a step to inspire additional advanced sound control systems. [ABSTRACT FROM AUTHOR]