Fast moving biomimetic ears

Abstract

Like many other mammals, bats are known to rely on spectral signatures to determine the directions of incoming sounds, especially in elevation. Because of its simple hardware and computational realizations, this principle could also be suitable for small, parsimonious biomimetic sonar systems. However, the biosonar systems of bat species in families such as the rhinolophids and hipposiderids often—but not always—concentrate most of the emitted energy within a narrow frequency band in order to pick up prey-induced Doppler signatures. It remains unclear how the use of such narrow-band biosonar pulses could be reconciled with direction-finding based on spectral signatures. A possible solution to this paradox could be provided by fast pinna motions in these animals that have been shown to produce readily perceivable Doppler-shift signatures in biomimetic reproductions. In the current work, such a biomimetic pinna with fast deformations has been used to map Doppler-shift signatures as a function of direction. For this purpose, the Doppler-shift signatures were clustered based on the similarity of their spectrogram-representations. Mapping the signatures' different cluster associations into direction space resulted in contiguous patches. Hence, it should be possible to obtain stable estimates of target direction based on the received Doppler signatures. <audio controls = “controls” style = “display: none;” > </audio> <audio controls = “controls” style = “display: none; “ > </audio>