Experimental study of the cochlear amplifier

描述(由申请人提供)作为流体机械频率分析器 复杂的环境声音，哺乳动物的耳蜗能够处理 宽动态范围内的幅度、相位和频率变化的声音 频率和时间分辨率都很高。这些能力归功于 显著的敏感性、非线性性和耳蜗尖调谐。至 为了了解耳蜗是如何工作的，人们提出了一种耳蜗放大器(CA) 由一些研究人员提出，它放大了基底膜(BM)的振动 唤醒了！通过低电平声音，提高机械频率的选择性。这个 CA被认为是通过从外毛细胞获取能量来工作的。 逐个周期的基础上，导致增强或抑制BM 根据频率的不同，通过正反馈或负反馈进行振动。 这项研究的目的是通过实验测试CA是否存在 使用我们新开发的信号处理方法并研究反馈 通过观察BM振动的位相关系提出CA假说 由声学和电学刺激引起的。以下具体目标将 被调查： I)EEOAE的长延时分量(LDC)是否来自 特征频率所在的BM，II)是否有LDC量 声能随耳蜗声敏感度的变化而变化； 增益在数值上大于1，并且它是否取决于电平 电流或EEOAE声压。最后，四)幅度 以及由声和电刺激引起的BM速度的相位 作为频率和强度的函数进行测量。位相关系 将用于测试与频率和电平相关的频率 CA的反馈机制。由于这种非侵入性的方法，广泛的 EEOAE的频率响应特性和固有的自检特性 在该方法中，在该拟议研究中CA的增益测量为 预计是准确可靠的。该项目提供了基本的 这两种实验数据都有助于加深我们对耳蜗机制的理解 并将多成分分析方法作为一种重要的分析工具 听觉研究和临床诊断。

DESCRIPTION (provided by applicant) As a hydromechanical frequency analyzer of complex environmental sounds, the mammalian cochlea is capable of processing amplitude, phase, and frequency-varying sounds in a wide dynamic range and with a high degree of frequency and time resolution. These capabilities are due to the remarkable sensitivity, nonlinearity, and sharp tuning of the cochlea. To understand how the cochlea works, a cochlear amplifier (CA) has been proposed by some investigators, which amplifies the basilar membrane (BM) vibration evoked ! by low level sound and enhances mechanical frequency selectivity. The CA is proposed to work by obtaining energy from the outer hair cells (OHCs) on a cycle-by-cycle basis, resulting in enhancement or suppression of the BM vibration through either positive or negative feedback, depending on frequency. The aim of this study is to experimentally test if the CA exists through the use of our newly developed signal processing method and to study the feedback hypothesis of the CA by observing the phase relationships of the BM vibrations evoked by acoustical and electrical stimuli. The following specific aims will be investigated: i) whether the long delay component (LDC) of the EEOAE comes from the characteristic frequency place on the BM, ii) whether the amount of LDC acoustical energy changes with cochlear sensitivity, and iii) whether the CA gain is numerically greater than one and whether it is dependent on the level of electrical current or the EEOAE sound pressure. Finally, iv) the amplitude and phase of the BM velocity evoked by acoustical and electrical stimuli will be measured as functions of frequency and intensity. The phase relationship beneath the OHCs will be used to test the frequency and level dependent feedback mechanism of the CA. Because of the noninvasive approach, the wide frequency response feature of the EEOAE, and the inherent self-testing property of the method, the gain measurement of the CA in this proposed study is expected to be accurate and reliable. The project provides fundamental experimental data both for advancing our understanding of cochlear mechanisms and for using multiple component analysis method as an important tool for auditory research and clinical diagnosis.