CLINICAL MEASURES OF AUDITORY LINEAR/NONLINEAR PROCESSES

临床听力学中的一个常见发现是，听力图相似的听力受损的人在言语感知方面的表现不同，他们从放大中获得的好处也不同。听力受损的听众之间缺乏同质性的一个原因是，听力图只提供了对耳蜗病理学的粗略估计。这可能是因为听力受损的听者在基本的耳蜗病理学上有所不同，而纯音阈值缺乏区分个体的敏感性。耳蜗病理学改变了耳蜗的转导过程。直接通过毛细胞结构的改变，或通过毛细胞转导所依赖的结构间接地改变机械力-电转导过程。描述这些过程的客观测量将描述耳蜗病的生理后果，并提供目前可用的更准确的感觉神经性听力损失的描述。本研究的长期目标是开发临床耳蜗声传导测量方法，以提供一种基于潜在病理生理学的新的感音神经性听力损失分类方案。随着毛细胞再生和基因治疗的未来发展，这些信息将有助于将治疗剂靶向生理部位，以及开发用于助听器和人工耳蜗植入的新信号处理算法。描述耳蜗声传导过程的指标由基于工程的非线性系统辨识方法和用于失真产物耳声发射的建模方法来估计。本研究的一个具体目的是确定最佳的信号参数，以获得人类耳蜗声传导的指标。在动物模型中，目的是确定中耳传递功能对耳蜗声传导过程的影响，并确定耳蜗声传导指数区分永久性听力损失耳的耳蜗病理学的敏感性和特异度。

A common finding in clinical audiology is that hearing-impaired listeners with similar audiograms perform differently on measures of speech perception and differ in the benefits they receive from amplification. One reason for the lack of homogeneity among hearing-impaired listeners is that the audiogram provides only a rough estimate of cochlear pathology. It is possible that hearing-impaired listeners differ in their underlying cochlear pathology and pure-tone thresholds lack the sensitivity to distinguish individuals. Cochlear pathology alters cochlear transduction processes. Mechano-electric transduction processes are modified, either directly through changes in hair cell structure, or indirectly through structures on which hair cell transduction relies. An objective measure that characterizes these processes will describe the physiologic consequences of cochlear disorders and supply a more accurate description of sensorineural hearing loss then presently available. The long term goal of this research is to develop clinical measures of cochlear transduction to provide a new categorization scheme of sensorineural hearing loss based on the underlying pathophysiology. With future developments in hair cell regeneration and gene therapy, this information will be useful for targeting therapeutic agents towards physiologic sites as well as for developing new signal processing algorithms for hearing aids and cochlear implants. Indices describing cochlear transduction processes are estimated from an engineering-based nonlinear systems identification procedure applied to cochlear potentials and from a modeling approach applied to distortion product otoacoustic emissions. One specific aim of this research is to determine the optimal signal parameters to obtain indices of cochlear transduction in humans. In an animal model, the aims are to determine the influence of the middle ear transfer function on cochlear transduction processes, and to determine the sensitivity and specificity of cochlear transduction indices to distinguish cochlear pathology in ears with permanent hearing loss.