Ambisonics and wideband matched-filter approach for bat biosonar study

Abstract

We previously introduced a method of bat echolocation signal measurement and analysis for target angle estimation using a custom-built high-frequency (20–80 kHz) soundfield microphone and spatial audio techniques. The method provided precise angle estimates of multiple targets. This presentation will provide details and results of expanding the processing of these spatial audio signals using a wideband matched-filter. The custom-built ultrasonic soundfield microphone recorded a static bat’s echolocation signals directly in front of the bat’s head. The measured audio signal in B-format was processed and reproduced for all directions with an increment of 1 deg in azimuth and elevation using Ambisonic audio processing techniques. A matched-filter algorithm was developed and produced wideband ambiguity functions (WAF) of transmitted signals from a high-frequency transmitter or bats. The wideband matched-filter outputs filter responses of the reproduced signals in time domain for all directions. The target estimate accompanying the strongest filter response provides the range, normal velocity, angle, and elevation of the target. This presentation shows the hardware and software development including experimental validation to establish this new method for bat biosonar study.We previously introduced a method of bat echolocation signal measurement and analysis for target angle estimation using a custom-built high-frequency (20–80 kHz) soundfield microphone and spatial audio techniques. The method provided precise angle estimates of multiple targets. This presentation will provide details and results of expanding the processing of these spatial audio signals using a wideband matched-filter. The custom-built ultrasonic soundfield microphone recorded a static bat’s echolocation signals directly in front of the bat’s head. The measured audio signal in B-format was processed and reproduced for all directions with an increment of 1 deg in azimuth and elevation using Ambisonic audio processing techniques. A matched-filter algorithm was developed and produced wideband ambiguity functions (WAF) of transmitted signals from a high-frequency transmitter or bats. The wideband matched-filter outputs filter responses of the reproduced signals in time domain for all directions. The target est...