Zhang Liujun, Yang Luhui, Zhang Ru, Müller Rolf
Department of Electrical and Computer Engineering, Virginia Tech, 1075 Life Science Circle, Blacksburg, Virginia 24061, USA.
Shandong University-Virginia Tech International Laboratory, Shandong University, Shanda South Road 27, Jinan, Shandong 250100, China.
J Acoust Soc Am. 2020 Aug;148(2):954. doi: 10.1121/10.0001774.
Old-World leaf-nosed bats (Hipposideridae) are echolocating bats with peculiar emission-side dynamics where beamforming baffles ("noseleaves") that surround the points of ultrasound emission (nostrils) change shape while diffracting the outgoing biosonar pulses. While prior work with numerical and robotic models has suggested that these noseleaf deformations could have an impact on the output characteristics of the bat's biosonar system, testing the hypothesis that this is the case in bats remains a critical step to be taken. The work presented here has tested the hypothesis that the noseleaf dynamics in a species of hipposiderid bat (Pratt's roundleaf bat, H. pratti) leads to time-variant acoustical properties on the output side of the bats' biosonar emission system. The time-variant effects of the noseleaf motion could be detected even in the presence of other sources of variability by comparing the distribution of pulse energy over the angle at different points in time. Furthermore, a convolutional neural network was able to classify the noseleaf motion state based on microphone array recordings with 85.3% accuracy. These results hence demonstrate that these nose-emitting bats have access to a substrate for behavioral flexibility on the emission-side of their biosonar systems.
旧大陆叶鼻蝠（蹄蝠科）是利用回声定位的蝙蝠，具有独特的发射端动态特性，即围绕超声发射点（鼻孔）的波束形成挡板（“鼻叶”）在使传出的生物声纳脉冲发生衍射时会改变形状。虽然之前利用数值模型和机器人模型开展的研究表明，这些鼻叶变形可能会对蝙蝠生物声纳系统的输出特性产生影响，但要验证蝙蝠确实如此这一假设，仍有关键的一步要走。本文所开展的研究验证了这样一个假设：一种蹄蝠科蝙蝠（普氏蹄蝠，H. pratti）的鼻叶动态特性会导致蝙蝠生物声纳发射系统输出端的声学特性随时间变化。通过比较不同时间点脉冲能量在角度上的分布，即使存在其他变异性来源，也能检测到鼻叶运动的时变效应。此外，一个卷积神经网络能够根据麦克风阵列记录以85.3%的准确率对鼻叶运动状态进行分类。因此，这些结果表明，这些通过鼻子发射超声波的蝙蝠在其生物声纳系统的发射端拥有实现行为灵活性的基础。
