Aertsen A M, Vlaming M S, Eggermont J J, Johannesma P I
Hear Res. 1986;21(1):17-40. doi: 10.1016/0378-5955(86)90043-2.
In an earlier paper (Vlaming et al., 1984) we reported on optical measurements (laser-doppler interferometry) of the vibrations characteristics of the grassfrog's tympanic membrane. In the present paper these measurements were extended to include acoustic measurements concerning the functional role of the mouth cavity in frog hearing. Based on these measurements a model of the frog's acoustic periphery, consisting of three coupled linear oscillators with three entrance ports for sound, was developed and analyzed mathematically to give the various relevant transfer functions. The model is characterized by six parameters, all of which could be estimated from the available experimental data. For frequencies up to some 1500 Hz the model adequately describes the experimental data, both our own and earlier, seemingly conflicting data in the literature. For higher frequencies deviations occur, possibly due to nonuniform vibrations of the membranes. The model was used to evaluate the monaural directional sensitivity of the frog under free-field stimulation. Essentially it behaves as a combined pressure-gradient receiver, with highly frequency-dependent directional sensitivity. Directional sensitivity of the tympanic membrane could be modulated drastically by changing the resonance properties of the mouth cavity, without affecting the intrinsic membrane properties. This, theoretically, allows the frog to manipulate its direction sensitivity by actively tuning the volume of its mouth cavity. In order to account for discrepancies with known properties of low-frequency auditory nerve fibers an additional, extra-tympanic channel was included into the model. The extended model, the second-channel possibly involving the opercularis complex, provides a good quantitative fit to the available data on tympanic membrane movement as well as auditory nerve activity. Finally, the model enables to simulate a (moving) sound source in space, while stimulating the frog via closed couplers.
在较早的一篇论文（弗拉明等人，1984年）中，我们报道了对草蛙鼓膜振动特性的光学测量（激光多普勒干涉测量法）。在本文中，这些测量得到了扩展，包括关于蛙口腔在听觉中功能作用的声学测量。基于这些测量，建立了一个蛙听觉外周模型，该模型由三个耦合的线性振荡器组成，有三个声音入口端口，并进行了数学分析以给出各种相关的传递函数。该模型由六个参数表征，所有这些参数都可以从现有的实验数据中估计出来。对于高达约1500赫兹的频率，该模型充分描述了我们自己以及文献中早期看似相互矛盾的实验数据。对于更高的频率出现了偏差，可能是由于膜的不均匀振动。该模型用于评估蛙在自由场刺激下的单耳方向敏感性。本质上，它表现为一个组合的压力梯度接收器，方向敏感性高度依赖于频率。通过改变口腔的共振特性，可以极大地调节鼓膜的方向敏感性，而不影响鼓膜的固有特性。从理论上讲，这使蛙能够通过主动调节口腔的容积来操纵其方向敏感性。为了解释与低频听觉神经纤维已知特性的差异，在模型中加入了一个额外的鼓膜外通道。扩展后的模型，第二个通道可能涉及动眼复合体，对鼓膜运动以及听觉神经活动的现有数据提供了很好的定量拟合。最后，该模型能够在通过封闭耦合器刺激蛙的同时，模拟空间中的（移动）声源。
