Bat biosonar echo analysis using spatial audio and wideband matched-filter techniques

Abstract

Bats and dolphins show tremendous aptitude in hunting prey in difficult conditions. These conditions include large amounts of clutter, perhaps reverberation, and interfering signals/noisy backgrounds. Bats have been extensively studied to learn more about how they detect, track, and intercept prey. One important aspect of many of these studies is to understand the acoustics around the bat’s head. In this work, a new reproduction methodology using spatial audio and matched-filter techniques will be presented. A custom-built tetrahedral 1st order soundfield microphone that captures high-frequency sound up to 80 kHz from all directions was developed to measure bat echoes in B-format. The three-dimensional echoes that the bat received, now in Ambisonic B-format were further processed using a wideband matched-filter. The matched-filter produces a wideband cross-ambiguity function (WAF) of received data and the transmitted signal for every 1 deg in azimuth and elevation. The thresholded matched-filter output provides precise estimates of bearing, elevation, range, and normal velocity. This poster will present details of the hardware and software development along with experimental results that illustrate the capabilities of this new approach.