Aging/ Psychophysical Estimates of Cochlear Nonlinearity

老年听众的语音清晰度通常比年轻听众差，特别是在存在噪声的情况下。尽管与年龄相关的听力灵敏度降低可能有助于这一发现，但最近的科学研究表明，即使在没有临床显著听力损失的情况下，也可能存在年龄诱导的阈上听觉处理缺陷。具体地，老化可能导致耳蜗非线性的降低，这进而可能不利地影响阈上处理。耳蜗非线性被认为反映了耳蜗外毛细胞的功能，是高灵敏度、尖锐频率调谐和通过抑制增强光谱对比度的原因。因此，非线性幅度的任何降低都可能导致一种或多种功能缺陷，可能包括受损的语音清晰度。这项研究的长期目标是进一步了解老年人的听觉处理。特别是，该项目将评估具有正常听力和轻度至中度听力损失的年轻和老年听众的耳蜗非线性的多个心理物理估计。对于所有提出的实验，将检查两个不同的信号频率，一个相对较低，一个相对较高;这些频率区域通常可能在非线性处理的强度上不同，因此年轻人和老年人之间的差异可能在较高的频率上更大。因此，本研究的目的是在同一组受试者中检查耳蜗非线性的多项措施，以确定是否存在与年龄相关的非线性下降。最终的目标是提供一个更好的理解老年听众所经历的听力困难。

Elderly listeners often experience poorer speech intelligibility than younger listeners, particularly in the presence of noise. Although an age- related reduction in hearing sensitivity likely contributes to this finding, recent scientific research suggests that an age-induced deficit in suprathreshold auditory processing may be present even in the absence of clinically significant hearing loss. Specifically, aging may result in a reduction in the cochlear nonlinearity which in turn may adversely affect suprathreshold processing. The cochlear nonlinearity, which is thought to reflect the functioning of the outer hair cells in the cochlea, is responsible for high sensitivity, sharp frequency tuning, and enhanced spectral contrasts via suppression. Thus, any reduction in the magnitude of the nonlinearity may result in one or more functional deficits, possibly including impaired speech intelligibility. The long-term goal of the proposed research is to further our understanding of the auditory processing of elderly listeners. In particular, this project will evaluate multiple psychophysical estimates of cochlear nonlinearity in young and aged listeners both with normal hearing and with mild- to-moderate hearing loss. For all proposed experiments, two different signal frequencies will be examined, one relatively low and one relatively high; these frequency regions may normally differ in their strength of nonlinear processing and thus differences between young and elderly listeners may be greater at the higher frequency. Thus, the purpose of this study is to examine multiple measures of cochlear nonlinearity in the same group of subjects to determine whether or not an age-related decline in the nonlinearity exists. The ultimate goal is to provide a better understanding of the listening difficulties experienced by elderly listeners.