Miles R N, Robert D, Hoy R R
Department of Mechanical Engineering, State University of New York at Binghamton 13902-6000, USA.
J Acoust Soc Am. 1995 Dec;98(6):3059-70. doi: 10.1121/1.413830.
An analysis is presented of the mechanical response to a sound field of the ears of the parasitoid fly Ormia ochracea. This animal shows a remarkable ability to detect the direction of an incident sound stimulus even though its acoustic sensory organs are in very close proximity to each other. This close proximity causes the arrival times of the sound pressures at the two ears to be less than 1 to 2 microseconds depending on the direction of propagation of the sound wave. The small differences in these two pressures must be processed by the animal in order to determine the incident direction of the sound. In this fly, the ears are so close together that they are actually joined by a cuticular structure which couples their motion mechanically and subsequently magnifies interaural differences. The use of a cuticular structure as a means to couple the ears to achieve directional sensitivity is novel and has not been reported in previous studies of directional hearing. An analytical model of the mechanical response of the ear to a sound stimulus is proposed which supports the claim that mechanical interaural coupling is the key to this animal's ability to localize sound sources. Predicted results for sound fields having a range of incident directions are presented and are found to agree very well with measurements.
本文对寄生蝇奥氏按蚊耳朵对声场的力学响应进行了分析。这种动物表现出非凡的能力，即使其听觉感觉器官彼此非常靠近，也能检测到入射声刺激的方向。这种紧密的距离使得根据声波传播方向，到达双耳的声压到达时间相差不到1到2微秒。动物必须处理这两种压力的微小差异，以确定声音的入射方向。在这种苍蝇中，耳朵靠得非常近，实际上通过一个表皮结构连接在一起，该结构在机械上耦合它们的运动，并随后放大双耳差异。使用表皮结构作为耦合耳朵以实现方向敏感性的手段是新颖的，并且在先前的方向听觉研究中尚未报道。提出了耳朵对声音刺激的力学响应的分析模型，该模型支持这样的观点，即机械双耳耦合是这种动物定位声源能力的关键。给出了具有一系列入射方向的声场预测结果，发现与测量结果非常吻合。
