COCHLEAR MECHANISMS OF FREQUENCY MICROSTRUCTURE

在这个提议中的实验被设计成调查 听阈和耳声的频率微结构 (OAE)现象。 频率微结构的临床分支 将通过检查耳蜗受损的耳朵来探索。 的 这项研究的最终目标将是开发更具体的 OAE诊断程序。 该提案的具体问题是： 1)频率微观结构的耳蜗机制是两者共同的吗 听阈和刺激频率耳声发射（SFOAE）？ 直接 比较了阈值和SFOAE的微观结构， 相同的正常耳朵（就最大/最小频率和振幅而言 偏移）将用于评估和对比几个相对的 关于潜在耳蜗机制的假设。 2)是频率 畸变产物耳声发射的显微结构 与多代源有关的频率函数？ 比较 DPOAE频率函数的测量与几个不同的主要 相互之间以及具有听觉阈值的刺激协议将 用于比较两种理论（艾伦和费伊，1993;秸秆， Neely和Gorga;，1997）3）经验结果是否可以通过，和 在耳蜗的数学模型中实现的假设 机械师？ 将尝试将随机波动纳入 耳蜗分区的数学模型中的几个方面 耳蜗（Neely，1993），它将再现经验数据，同时允许 模型保持稳定。 4)频率损失是否微观结构 在没有听力损失的情况下发生衰老？ 频率微结构 在正常听力和轻度听力损失范围内， 两个年龄组的成年人仔细匹配听力阈值。 5)DPOAE频率微结构能解释 DPOAE在临床诊断中的特异性？ 基于早期 实验DPOAE频率函数的缩短协议将是 在听力正常至轻度的大量受试者中进行评估 听力损失，试图改善听觉的临床估计 阈值

The experiments in this proposal are designed to investigate the frequency microstructure of both auditory thresholds and otoacoustic (OAE) phenomena. The clinical ramifications of frequency microstructure will be explored by examining ears with cochlear impairment. The ultimate goal of this line of research will be to develop more specific diagnostic OAE procedure. The specific questions of the proposal are: 1) Is the cochlear mechanism for frequency microstructure common to both auditory threshold and stimulus frequency OAEs (SFOAEs)? Direct comparison of the microstructure of both threshold and SFOAE from the same normal ears (in terms of frequencies of maxima/minima and amplitude excursion) will be used to evaluate and contrast several opposing hypotheses regarding underlying cochlear mechanisms. 2) Is frequency microstructure in distortion product otoacoustic emissions (DPOAE) frequency functions related to multiple generation sources? Comparison of DPOAE frequency functions as measured with several different primary stimulus protocols among each other and with auditory thresholds will be used to compare between two theories (Allen and Fahey, 1993; Stover, Neely and Gorga;, 1997) 3) Can empirical results be reproduced by, and the hypothesis implemented in a mathematical model of cochlear mechanics? Attempts will be made to incorporate random fluctuations in several aspects of the cochlear partition in a mathematical model of the cochlea (Neely, 1993) which will reproduce empirical data while allowing the model to remain stable. 4) Does loss of frequency microstructure occur in aging in the absence of hearing loss? Frequency microstructure across normal hearing and mild hearing loss ranges will be compared for two age groups of adults carefully matched for audiometric threshold. 5) Can DPOAE frequency microstructure account for the lack of specificity of DPOAEs in clinical diagnostics? Based on earlier experiments a shortened protocol of DPOAE frequency functions will be evaluated on a large population of subjects with normal hearing to mild hearing losses in an attempt to improve clinical estimation of auditory threshold.