The cochlea is part of the inner ear and its mechanical response provides us with many aspects of our amazingly sensitive and selective hearing. The human cochlea is a coiled tube, with two main fluid chambers running along its length, separated by a 35 mm-long flexible partition that has its own internal dynamics. A dispersive wave can propagate along the cochlea due to the interaction between the inertia of the fluid and the dynamics of the partition. This partition includes about 12 000 outer hair cells, which have different structures, on a micrometre and a nanometre scale, and act both as motional sensors and as motional actuators. The local feedback action of all these cells amplifies the motion inside the inner ear by more than 40 dB at low sound pressure levels. The feedback loops become saturated at higher sound pressure levels, however, so that the feedback gain is reduced, leading to a compression of the dynamic range in the cochlear amplifier. This helps the sensory cells, with a dynamic range of only about 30 dB, to respond to sounds with a dynamic range of more than 120 dB. The active and nonlinear nature of the dynamics within the cochlea give rise to a number of other phenomena, such as otoacoustic emissions, which can be used as a diagnostic test for hearing problems in newborn children, for example. In this paper we view the mechanical action of the cochlea as a smart structure. In particular a simplified wave model of the cochlear dynamics is reviewed that represents its essential features. This can be used to predict the motion along the cochlea when the cochlea is passive, at high levels, and also the effect of the cochlear amplifier, at low levels.

中文翻译：

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作为智能结构的耳蜗

耳蜗是内耳的一部分，它的机械反应为我们提供了惊人的灵敏和选择性听力的许多方面。人类耳蜗是一个盘绕管，沿其长度方向有两个主要的流体室，由一个 35 毫米长的柔性隔板隔开，该隔板具有自己的内部动力学。由于流体的惯性和隔板的动力学之间的相互作用，色散波可以沿着耳蜗传播。该分区包括大约 12 000 个外毛细胞，它们具有微米和纳米尺度的不同结构，既可用作运动传感器，又可用作运动执行器。在低声压级下，所有这些细胞的局部反馈作用将内耳内的运动放大了 40 dB 以上。反馈回路在较高声压级时变得饱和，但是，从而降低反馈增益，从而压缩耳蜗放大器的动态范围。这有助于动态范围仅为 30 dB 左右的感觉细胞对动态范围超过 120 dB 的声音做出响应。耳蜗内动态的主动和非线性性质会引起许多其他现象，例如耳声发射，例如，可用作新生儿听力问题的诊断测试。在本文中，我们将耳蜗的机械作用视为一种智能结构。特别是审查了代表其基本特征的耳蜗动力学的简化波模型。这可用于预测当耳蜗被动时在高电平时沿耳蜗的运动，以及在低电平时预测耳蜗放大器的影响。