Katydids (bush-crickets) are endowed with tympanal ears located in their forelegs' tibiae. The tympana are backed by an air-filled tube, the acoustic trachea, which transfers the sound stimulus from a spiracular opening on the thorax to the internal side of the tympanic membranes (TM). In katydids the sound stimulus reaches both the external and internal side of the membranes, and the tympanal vibrations are then transferred to the hearing organ crista acustica (CA) that contains the fluid-immersed mechanoreceptors. Hence the tympana are principally involved in transmitting and converting airborne sound into fluid vibrations that stimulate the auditory sensilla. Consequently, what is the transmission power to the CA? Are the TM tuned to a certain frequency? To investigate this, the surface normal acoustic impedance of the TM is calculated using finite-element analysis in the katydid Copiphora gorgonensis. From this, the reflectance and transmittance are obtained at the TM. Based on the impedance results obtained from the pressure recordings at TM and the velocity field calculations in the AT, in the frequency range 5–40 kHz, it is concluded that the tympana have considerably higher transmission around 23 kHz, corresponding to the dominant frequency of the male pure-tone calling song in this species.

中文翻译：

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关于katydidCopiphora gorgonensis（Insecta：直翅目：Tettigoniidae）的鼓膜阻抗

Katydids（灌木cri）的前腿胫骨处有鼓膜耳朵。鼓膜由充气管（声管）支持，该管将声音刺激从胸腔的螺旋形开口转移到鼓膜（TM）的内侧。在katydids中，声音刺激同时到达膜的内侧和外侧，然后将鼓膜振动传递到听觉cr（CA）包含液浸式机械感受器。因此，鼓膜主要参与将空气传播的声音传输并将其转换为液体振动，从而刺激听觉感觉。因此，CA的传输功率是多少？TM是否已调至特定频率？为了对此进行研究，使用有限元分析法对ty蛇冠pi的表面法向声阻抗进行了计算。。由此，在TM处获得反射率和透射率。根据在TM处的压力记录和AT中的速度场计算获得的阻抗结果，在5–40 kHz频率范围内，得出的结论是，该鼓音在23 kHz附近具有明显更高的透射率，这对应于该物种中的男性纯音呼叫歌曲。