Department of Mechanical Engineering, Virginia Tech, 460 Old Turner Street, Blacksburg, Virginia 24061, USA.
Department of Neuroscience, Brown University, 185 Meeting Street, Providence, Rhode Island 02912, USA.
J Acoust Soc Am. 2019 Dec;146(6):4525. doi: 10.1121/1.5139652.
Numerous bat species emit wideband frequency-modulated signals for echolocation to hunt prey and avoid obstacles. Research investigating the behavioral and physiological responses of bats to echoes typically includes analysis of acoustic signals from microphones and/or microphone arrays, using time difference of arrival between array elements or the microphones to locate flying bats (azimuth and elevation). This has provided insight into transmission adaptations such as pulse duration and duty cycle with respect to target distance, clutter, and interferers. Microphones recording transmitted signals and echoes near a stationary bat provide sound pressure as a function of time but no directional information. In this work, the authors propose a spatial audio/soundfield microphone array to both track bats in flight and pinpoint the directions of echoes received by a bat. The authors introduce an ultrasonic (20-80 kHz) tetrahedral soundfield microphone to capture bat sounds up to 80 kHz. A spatial audio decoding technique called high angular resolution planewave expansion (HARPEx) supplies angle and elevation estimates, either for a flying bat based on the bat pulses or for targets based on echoes. Experiments using the soundfield microphone and HARPEx show that the approach accurately estimates the sound direction of arrival in both scenarios.
许多蝙蝠物种会发出宽带调频信号，用于回声定位以捕食猎物和避开障碍物。研究蝙蝠对回声的行为和生理反应的研究通常包括对来自麦克风和/或麦克风阵列的声信号进行分析，使用阵列元件或麦克风之间的到达时间差来定位飞行中的蝙蝠（方位角和仰角）。这为研究蝙蝠提供了有关脉冲持续时间和占空比与目标距离、杂波和干扰物之间的传输适应的深入了解。在静止蝙蝠附近记录传输信号和回声的麦克风提供了随时间变化的声压，但没有指向性信息。在这项工作中，作者提出了一种空间音频/声场麦克风阵列，用于跟踪飞行中的蝙蝠并确定蝙蝠接收到的回声的方向。作者引入了一种超声波（20-80 kHz）四面体声场麦克风，可捕获高达 80 kHz 的蝙蝠声音。一种称为高角分辨率平面波扩展（HARPEx）的空间音频解码技术可提供基于蝙蝠脉冲的飞行蝙蝠或基于回声的目标的角度和仰角估计。使用声场麦克风和 HARPEx 的实验表明，该方法在这两种情况下都能准确估计声到达方向。
