Faculty of Life and Medical Sciences, Doshisha University, Kyōtanabe, Kyoto, Japan.
Department of Mathematical and Life Sciences, Hiroshima University, Higashihiroshima, Hiroshima, Japan.
BMC Biol. 2022 Mar 14;20(1):59. doi: 10.1186/s12915-022-01253-y.
Echolocating bats use echo information to perceive space, control their behavior, and adjust flight navigation strategies in various environments. However, the echolocation behavior of bats, including echo information, has not been thoroughly investigated as it is technically difficult to measure all the echoes that reach the bats during flight, even with the conventional telemetry microphones currently in use. Therefore, we attempted to reproduce the echoes received at the location of bats during flight by combining acoustic simulation and behavioral experiments with acoustic measurements. By using acoustic simulation, echoes can be reproduced as temporal waveforms (including diffracted waves and multiple reflections), and detailed echo analysis is possible even in complex obstacle environments.
We visualized the spatiotemporal changes in the echo incidence points detected by bats during flight, which enabled us to investigate the "echo space" revealed through echolocation for the first time. We then hypothesized that by observing the differences in the "echo space" before and after spatial learning, the bats' attentional position would change. To test this hypothesis, we examined how the distribution of visualized echoes concentrated at the obstacle edges after the bats became more familiar with their environment. The echo incidence points appeared near the edge even when the pulse direction was not toward the edge. Furthermore, it was found that the echo direction correlated with the turn rate of the bat's flight path, revealing for the first time the relationship between the echo direction and the bat's flight path.
We were able to clarify for the first time how echoes space affects echolocation behavior in bats by combining acoustic simulations and behavioral experiments.
回声定位蝙蝠利用回声信息感知空间、控制行为，并在各种环境中调整飞行导航策略。然而，蝙蝠的回声定位行为，包括回声信息，尚未被彻底研究，因为即使使用目前常规的遥测麦克风，技术上也很难测量在飞行过程中到达蝙蝠的所有回声。因此，我们试图通过结合声学模拟和行为实验与声学测量，重现蝙蝠在飞行过程中接收到的回声。通过使用声学模拟，可以将回声重现为时间波形（包括衍射波和多次反射），即使在复杂的障碍物环境中，也可以进行详细的回声分析。
我们可视化了蝙蝠在飞行过程中探测到的回声入射点的时空变化，这使我们能够首次研究通过回声定位揭示的“回声空间”。然后，我们假设通过观察空间学习前后“回声空间”的差异，蝙蝠的注意力位置会发生变化。为了验证这一假设，我们研究了蝙蝠在对环境变得更加熟悉后，集中在障碍物边缘的可视化回声的分布情况。即使脉冲方向不是朝向边缘，回声入射点也出现在边缘附近。此外，还发现回声方向与蝙蝠飞行路径的转弯率相关，这首次揭示了回声方向与蝙蝠飞行路径之间的关系。
我们通过结合声学模拟和行为实验，首次能够阐明回声空间如何影响蝙蝠的回声定位行为。
