Using bat auditory modelling for object discrimination and echo separation tasks

This paper proposes a computational echolocation model that can be used for discrimination of the specific target object and reconstruction of the acoustic information from multiple overlapping echoes returning back from that target. An acoustic model for estimation of the backscattering impulse responses of a rigid disk has been developed and employed in order to simulate reflection and scattering of FM signal from the disk surface and edges. By rotating the disk around its central axis reflected echo patterns from its edges change allowing for small time variation between arrivals of each individual echo component. This represents the scenario of a flying insect where the distances from the bat to the insect's head, body and wings are slightly different with each returning a contribution to the overall echo. The echolocation signal obtained from the rotating disk is further encoded into the spectrogram-like format characteristic for the mammalian auditory system. The simulation results presented in this paper demonstrate that the proposed model is able to distinguish between overlapping echoes from the spectrogram-like forms of the echolocation signals.