COMPUTER MODELING OF ACOUSTIC BEAM FORMATION IN DELPHINUS-DELPHIS
COMPUTER MODELING OF ACOUSTIC BEAM FORMATION IN DELPHINUS-DELPHIS
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DOI：
10.1121/1.404424
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发表时间：
1992-11-01
影响因子：
2.4
通讯作者：
NORRIS, KS
中科院分区：
文献类型：
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作者：
AROYAN, JL;CRANFORD, TW;NORRIS, KS
已经确定一些海豚具有发达的声音定位（回声定位）和信息收集能力，尽管对声音产生和波束形成系统知之甚少。在回声定位过程中，海豚使用从前额和喙部发出的狭窄聚焦声束。本研究的主要目的是模拟解剖结构对光束形成的影响，并测试各种假设声源位置的可行性。从矢状旁x线CT扫描的轮廓被用来构建一个普通海豚头部的二维模型。有限差分技术用于模拟声音在非均匀流体组织中的传播。初步的模拟证实了光束的形成主要是由于头骨和头骨支撑的气囊表面的反射。对于测试的频率，波束角度最接近实验方法测量的位于模型中称为猴唇/背囊（MLDB）复合体区域的源。结果表明：(1)颅骨和气囊在梁的形成中起核心作用；(2)反射组织的几何形状比指定的确切声学特性更重要；(3)所测量级的甜瓜速度剖面能够产生轻微的聚焦效应；(4)当声源放置在MLDB复合体附近时，实验观察到的波束模式在模拟的所有频率下都是最接近的。
It has been established that some dolphins possess well-developed acoustic orientation (echolocation) and information gathering abilities, though substantially less is known about the system of sound generation and beam formation. Dolphins use a narrowly focused sound beam that emanates from the forehead and rostrum during echolocation. The primary objectives of this study were to simulate the effects of anatomical structure on beam formation, and to test the viability of various hypothetical sound source locations. Outlines from parasagittal x-ray CT scans were used to construct a 2-D model of the head of the common dolphin, Delphinus delphis. Finite difference techniques were used to simulate sound propagation through tissues modeled as inhomogeneous fluids. Preliminary simulations confirm that beam formation results primarily from reflection off of the skull and the skull-supported air sac surfaces. For the frequencies tested, beam angles best approximate those measured by experimental methods for a source located in a region of the model referred to as the monkey lip/dorsal bursae (MLDB) complex. The results suggest that: (1) the skull and air sacs play the central role in beam formation; (2) the geometry of reflective tissue is more important than the exact acoustical properties assigned; (3) a melon velocity profile of the magnitude tested is capable of mild focusing effects; and (4) experimentally observed beam patterns are best approximated at all frequencies simulated when the sound source is placed in the vicinity of the MLDB complex.