Acoustic designs of orthopteran insects

蟋蟀和蝈蝈通过摩擦前翅发出声音。歌曲是雄性发出来吸引雌性交配，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的内部气管支撑。与人类相比，这些昆虫的信号系统，无论是发生器还是接收器，都是小型化的。我们正试图了解如此微小和短暂的结构是如何传播如此长波长的声音的。我们对发电机的研究是关于机翼下方体腔的形状和体积如何影响广播声音的响度。一些物种有突出的声音反射身体区域，而另一些则完全将它们的发声前翼封闭在一个腔室中：我们正在测试这些身体变化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，它们无法通过身体的“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左右差异。相反，它们通过体内的气管传导声音，因此声波在不同的时间到达每个耳膜的前后，经过不同的路径长度。当蟋蟀转动时，路径会相对改变，并在鼓膜处产生声音干扰，从而提供可用的双耳定位线索。我们正在比较许多不同种类蟋蟀耳朵内部气管的排列。最后，这项研究是对高性能声音信号的难度的研究，就像音乐会钢琴家所需的技能水平一样，是否可以作为雌性蝈蝈在唱歌的雄性中选择更好伴侣的诚实评估的基础。我们改变雄性的信号质量，观察雌性的偏好。这项工作的共同主题是深入了解声音是如何被小型化的动物器官处理的。人们希望发现适应性，从而改进类似小型设备的设计，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.