Numerical analysis of biosonar beamforming mechanisms and strategies in bats
Numerical analysis of biosonar beamforming mechanisms and strategies in bats
复制标题
蝙蝠生物声纳波束形成机制和策略的数值分析。
DOI：
10.1121/1.3365246
复制
发表时间：
2010-09-01
影响因子：
2.4
通讯作者：
Mueller, Rolf
中科院分区：
文献类型：
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作者：
Mueller, Rolf
波束形成对大多数声纳系统的功能至关重要。蝙蝠明显的鼻叶和耳廓形状表明，基于出射和入射超声波的绕射形成波束的机制在蝙蝠生物声纳中发挥着重要作用。数值方法可以用来研究挡板几何形状、声学机制和所产生的波束方向图之间的关系。数值方法的主要优点是：高效、高分辨率的波束方向图估计，近场幅度的空间密集预测，以及基本形状表示的可塑性。综述了一种将基于Helmholtz方程简谐解的有限元形式的近场预测和基于Kirchhoff积分的自由场投影相结合来获得远场波束方向图估计的数值方法。这种方法已经被用来预测物理波束形成机制，例如马蹄蝠鼻叶中半开谐振腔的频率相关波束形成，以及假吸血蝙蝠通过扩展耳廓孔径和皮肤褶皱来缩小波束。以中国小节为例，讨论了生物声纳波束方向图的精细结构，并以棕色长耳蝙蝠为例，说明了波束方向图所传递的空间信息的评估方法。
Beamforming is critical to the function of most sonar systems. The conspicuous noseleaf and pinna shapes in bats suggest that beamforming mechanisms based on diffraction of the outgoing and incoming ultrasonic waves play a major role in bat biosonar. Numerical methods can be used to investigate the relationships between baffle geometry, acoustic mechanisms, and resulting beampatterns. Key advantages of numerical approaches are: efficient, high-resolution estimation of beampatterns, spatially dense predictions of near-field amplitudes, and the malleability of the underlying shape representations. A numerical approach that combines near-field predictions based on a finite-element formulation for harmonic solutions to the Helmholtz equation with a free-field projection based on the Kirchhoff integral to obtain estimates of the far-field beampattern is reviewed. This method has been used to predict physical beamforming mechanisms such as frequency-dependent beamforming with half-open resonance cavities in the noseleaf of horseshoe bats and beam narrowing through extension of the pinna aperture with skin folds in false vampire bats. The fine structure of biosonar beampatterns is discussed for the case of the Chinese noctule and methods for assessing the spatial information conveyed by beampatterns are demonstrated for the brown long-eared bat.