Peake W T, Ling A
J Acoust Soc Am. 1980 May;67(5):1736-45. doi: 10.1121/1.384300.
In the alligator lizard the entire basilar membrane is accessible for measurements of its velocity by the Mössbauer method. Tests of the method indicate (1) the Mössbauer source can be placed on the basilar membrane without altering the signal-transmission properties of the cochlea, and (2) the source adheres to the basilar membrane. Isovelocity curves (IVCs) were constructed by plotting (as a function of tone frequency) the sound-pressure level at the tympanic membrane required to produce a specified velocity amplitude. IVCs from 21 lizards for source locations spanning the length of the basilar membrane indicate that basilar-membrane velocity does not vary systematically with longitudinal location as it does in mammalian cochleas. Measurements of velocity waveforms in two lizards do not indicate substantial nonlinearity in the inner-ear mechanical system. The frequency dependence of the basilar-membrane velocity is similar to that of the extrastapes velocity over the range 0.4 to 2 kHz. Thus, the tonotopic organization and frequency selectivity, which have been previously demonstrated in this species in responses of both auditory-nerve fibers and cells of the receptor organ, are apparently not primarily determined by basilar-membrane motion.
在鳄蜥中，整个基底膜都可通过穆斯堡尔方法测量其速度。该方法的测试表明：（1）穆斯堡尔源可放置在基底膜上而不改变耳蜗的信号传输特性；（2）源会附着在基底膜上。等速度曲线（IVC）是通过绘制（作为音调频率的函数）产生特定速度幅值所需的鼓膜处声压级来构建的。来自21只蜥蜴的、源位置跨越基底膜长度的IVC表明，基底膜速度不像在哺乳动物耳蜗中那样随纵向位置系统地变化。对两只蜥蜴的速度波形测量未表明内耳机械系统存在明显的非线性。在0.4至2千赫范围内，基底膜速度的频率依赖性与镫骨外速度的频率依赖性相似。因此，此前在该物种的听觉神经纤维和感受器器官细胞的反应中已得到证实的音调组织和频率选择性，显然并非主要由基底膜运动决定。
