仿生波束形成挡板的时变行为特性研究。

Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA.

J Acoust Soc Am. 2013 Feb;133(2):1141-50. doi: 10.1121/1.4773272.

Horseshoe bats can actively change the shapes of their noseleaves and outer ears on time scales that are comparable to the duration of the biosonar pulses and echoes. When the shape deformations and the emission or reception of the ultrasonic signals overlap in time, the result is a time-variant diffraction process. Such a dynamic process provides additional flexibility that could potentially be used to enhance the encoding of sensory information. However, such a function remains hypothetical at present. To investigate the time-variant properties of deforming baffles such as the outer ears of horseshoe bats, the acoustic behavior of a biomimetic microphone baffle modeled on these biological structures has been investigated. The methods employed to characterize this device included representations in the time-delay domain as well as in the time-frequency domain. It was found that characterization methods which do not employ Fourier transforms revealed even more substantial time-variant effects than were apparent from time-frequency domain characterizations such as beampatterns obtained for different times in the deformation cycle. Furthermore, conspicuous correlates of asymmetries in the time-variant physical shapes were found in some characterizations that could be used to link dynamic baffle geometry with acoustic behavior.

马蹄蝠可以主动改变鼻叶和外耳的形状，其时间尺度与生物声纳脉冲和回波的持续时间相当。当形状变形和超声波信号的发射或接收在时间上重叠时，就会产生时变的绕射过程。这种动态过程提供了额外的灵活性，可能被用来增强感觉信息的编码。然而，这种功能目前仍处于假设阶段。为了研究变形挡板（如马蹄蝠的外耳）的时变特性，对基于这些生物结构的仿生麦克风挡板的声行为进行了研究。用于描述该装置的方法包括在延时域和时频域中的表示。结果发现，与时间频率域特征（例如，在变形周期的不同时间获得的声图）相比，不采用傅里叶变换的特征化方法揭示了更为显著的时变效应。此外，在一些特征化中发现了时变物理形状不对称的明显相关性，这些相关性可用于将动态挡板几何形状与声行为联系起来。