Walker V A, Peremans H, Hallam J C
Department of Artificial Intelligence, University of Edinburgh, United Kingdom.
J Acoust Soc Am. 1998 Jul;104(1):569-79. doi: 10.1121/1.423256.
Bats, which echolocate using broadband calls, are believed to employ the passive acoustic filtering properties of the head and pinnae to provide spectral cues which encode 3-D target angle. Microchiropteran species whose calls consist of a single, constant frequency harmonic (i.e., some species in the families Rhinolophidae and Hipposideridae) may create additional acoustic localization cues via vigorous pinna movements. In this work, two types of echolocation cues generated by moving a pair of receivers aboard a model sensor head are investigated. In the first case, it is supposed that a common 3-D echolocation principle employed by all bats is the creation of alternative viewing perspectives, and that constant frequency (CF) echolocators use pinna movement rather than morphology to alter the acoustic axes of their perceptual systems. Alternatively, it is possible rhinolophids and hipposiderids move their ears to create dynamic cues--in the form of frequency and amplitude modulations--which vary systematically with target elevation. Here the use of binaural and monaural timing cues derived from amplitude modulated echo envelopes are investigated. In this case, pinna mobility provides an echolocator with a mechanism for creating dramatic temporal cues for directional sensing which, unlike interaural timing differences, do not degrade with head size.
蝙蝠利用宽带叫声进行回声定位，据信它们利用头部和耳廓的被动声学滤波特性来提供编码三维目标角度的频谱线索。其叫声由单一、恒定频率谐波组成的小型翼手目物种（即菊头蝠科和蹄蝠科的一些物种）可能通过剧烈的耳廓运动产生额外的声学定位线索。在这项研究中，研究了通过在模型传感器头部移动一对接收器产生的两种回声定位线索。在第一种情况下，假设所有蝙蝠采用的一种常见的三维回声定位原理是创建不同的视角，并且恒定频率（CF）回声定位器利用耳廓运动而非形态来改变其感知系统的声轴。或者，菊头蝠和蹄蝠有可能移动它们的耳朵以产生动态线索——以频率和幅度调制的形式——这些线索随目标高度而系统地变化。在此研究了利用从幅度调制回声包络中获取的双耳和单耳时间线索。在这种情况下，耳廓的可动性为回声定位器提供了一种机制，用于创建用于方向感知的显著时间线索，与双耳时间差不同，这种线索不会随着头部尺寸的增大而减弱。
