ELECTRICALLY EVOKED OTOACOUSTIC EMISSION

对于复杂环境声音的感知，正常哺乳动物的耳朵具有极宽的动态范围和高频率选择性。 这些听觉能力是通过耳蜗的高灵敏度、非线性和尖锐调谐来实现的。 本文提出了一种耳蜗放大器，用于放大低频声诱发的基底膜振动，增强机械频率选择性。 一个被广泛接受的推测是，放大器通过从外毛细胞（OHC）获得能量来工作。 虽然孤立的OHC电活动在体外已被深入研究，耳蜗放大器的理论被普遍接受，OHC电活动在耳蜗放大器的作用还没有在体内和敏感的耳蜗进行测试。 所提出的工作的长期目标是确定耳蜗放大器反馈系统是否利用OHC产生的能量。 为了实现这一长期目标，电诱发耳声发射（EEOAE）的特性是必不可少的。 在本初步研究中，将通过关注EEOAE的精细结构来研究EEOAE。 我们的工作假设是，耳道测量EEOAE是一个向量总和的多个组成部分的电诱发的机械反应在耳蜗。 EEOAE的精细结构是不同成分的抵消和增强的结果，并且精细结构指示敏感耳蜗的正常机械性能。为了保持耳蜗敏感性，将使用耳蜗外电刺激动物模型来产生EEOAE。 本文提出了一种单频信号多分量检测的方法来分析EEOAE。 所提出的研究的具体目的是调查i）EEOAE的精细结构是如何产生的; ii）EEOAE精细结构与耳蜗敏感性之间的关系;以及iii）EEOAE和声诱发立方畸变产物耳声发射（DPOAE）精细结构之间的对应关系。 将观察EEOAE的每个分量对耳蜗灵敏度变化和同时呈现的声刺激的响应。 还将研究EEOAE和DPOAE之间多个分量的相似性。从拟议的实验结果将提供证据表明，精细结构的EEOAE的多组分的相互作用的结果，多组分分析方法是一种可靠的方法，用于量化的耳声发射的精细结构。

For the perception of complex environmental sounds, the normal mammalian ear has an extremely wide dynamic range and high frequency selectivity. These auditory capabilities are achieved by cochlear high sensitivity, nonlinearity and sharp tuning. A cochlear amplifier has been proposed to amplify the basilarmembrane vibration evoked by low level sound and enhance mechanical frequency selectivity. A widely accepted speculation is that the amplifier works by obtaining energy from the outer hair cells (OHCs). Although isolated OHC electromotility in vitro has been intensively studied and the cochlear amplifier theory is generally accepted, the role of the OHC electromotility in the cochlear amplifier has not been tested in vivo and in sensitive cochleae. The long-term objective of the proposed work is to determine whether a cochlear amplifier feedback system utilizes OHC-generated energy. In order to achieve the long-term goal, it is essential to characterize the electrically evoked otoacoustic emissions (EEOAE). The EEOAE will be investigated in this initial study by focusing on the fine structure of the EEOAE. Our working hypothesis is that the ear canal-measured EEOAE is a vector summation of the multicomponents of the electrically evoked mechanical response in the cochlea. The fine structure of the EEOAE results from the cancellation and enhancement of the different components, and the fine structure indicates normal mechanical properties of a sensitive cochlea. To preserve cochlear sensitivity, an extracochlear electrical stimulation animal model will be used to generate the EEOAE. A method for detecting multicomponents of a single frequency signal will be implemented to analyze the EEOAE. The specific aims of the proposed study are to investigate i) how the fine structure of the EEOAE is generated; ii) what the relationship is between the EEOAE fine structure and cochlear sensitivity; and iii) what the correspondence is between the EEOAE and acoustically evoked cubic distortion product otoacoustic emission (DPOAE) fine structures. The responses of each of the components of the EEOAE to cochlear sensitivity changes and a simultaneously presented acoustic stimulus will be observed. Similarity of the multiple components between the EEOAE and the DPOAE will also be studied. Results from the proposed experiments will provide evidence that the fine structure results from the interaction of the multicomponents of the EEOAE, and that the multicomponent analysis method is a reliable method for quantification of the fine structure of the otoacoustic emissions.