Acoustic designs of orthopteran insects

蟋蟀和麒麟通过摩擦它们的前翼而发出声音。歌声是由雄性产生的，以吸引雌性交配，在一些物种中，也用于雄性竞争。它们前腿上的鼓膜由身体其他部位打开的内部空气管支撑。与人类相比，这些昆虫的信号系统，无论是产生器还是接收器，都是微型化的。我们正在试图了解这种微小而短的结构是如何发挥作用来传播如此长的声音波长的。我们对发电机的研究询问机翼下方体腔的形状和体积如何影响广播声音的响度。一些物种有投射声音反射的身体区域，而另一些物种则将它们发出声音的前翼完全封闭在一个房间里：我们正在测试这些身体修改如何影响昆虫周围产生的声场。相对于波长而言，蟋蟀是如此之小，无法通过身体的“声影”来确定远处呼叫者的位置：它们的身体不会产生声音强度的横向差异。取而代之的是，他们通过内部空气管将声音传导到全身，因此声波在不同的路径长度后，在不同的时间到达每个耳膜的前面和后面。当蟋蟀转动时，路径相对于彼此改变，并在鼓膜处引起声音干扰，从而提供有用的双耳定位提示。我们正在比较许多不同种类的蟋蟀耳朵的内部空气管排列。最后，这项研究是关于高性能声学信号的难度，就像音乐会钢琴家所需的技能水平一样，是否可以作为雌性katydids在唱歌的雄性中选择更好的配偶的诚实评估的基础。我们改变男性的信号质量，观察女性的偏好。这项工作的共同主题是深入了解声音是如何被最小化的动物器官处理的。一个人希望发现的适应将建议改进类似的小型设备的设计，例如用于对抗人类耳聋的助听器。

Crickets and katydids make sounds by rubbing their forewings together. Songs are generated by males to attract females for mating and in some species also used in male rivalry. Eardrums on their forelegs are backed by internal air tubes opening elsewhere on the body. Compared to humans, the signal system of these insects, both generators and receivers, is minaturized. We are trying to understand how such tiny and short structures function to broadcast sound wavelengths that are so long. Our research into generators asks how the shape and volume of body cavities below the wings affect the loudness of the broadcast sound. Some species have projecting sound-reflective body regions, while others completely enclose their sound-making forewings in a chamber: we are testing how these body modifications affect the sound field created around the insect. Being so small relative to wavelength, crickets are unable to fix the position of a distant caller by body 'sound shadow': no side-to-side differences in sound intensity are created by their body. Instead they conduct the sound across their body via internal air tubes and so sound waves reach the front and back of each eardrum at different times, after travelling different path lengths. As the cricket turns, the paths change relative to each other and cause sound interference at the eardrum giving usable binaural localization cues. We are comparing the internal air-tube arangements of the ears of many different cricket species. Finally, this research is a study of whether the difficulty of high-performance acoustic signalling, like the skill level needed by a concert pianist, can be the basis of honest assessment of a better mate by female katydids choosing among singing males. We change a male's signal quality and observe female preferences. The common theme of this work is gaining insight into how sound is processed by minaturized animal organs. One hopes to discover adaptations that will suggest improved design of similarly small devices such as the hearing aids used to counter human deafness.