DEVELOPMENT OF HUMAN COCHLEAR FUNCTION

描述：本项目的长期目标是调查 人类耳蜗功能的发展。 这种理解将提供一个 更精确识别耳蜗功能障碍的框架，提供 支持开发和改进听觉假体， 测试人类听觉发展的一般理论。 长期目标将是 通过研究时间进程和频率依赖性 发展（1）耳蜗调谐，（2）主动耳蜗力学，和（3） 畸变产物耳声发射耳蜗传出功能 （DPOAE）方法。 DPOAE是由DPOAE产生的互调产物。 正常的耳蜗，当同时呈现两个音调（f1，f2）时。 他们提供了一种非侵入性的，特定频率的耳蜗生理学探针 在人类身上。 本课题包括三个实验：1）实验一，DPOAE 同侧抑制调谐曲线将提供对 在孕龄为29 - 36周的新生儿中进行耳蜗调谐， 足月婴儿和听力正常的成年受试者在五个f2频率下： 1100、2500、5600、9000和12，500 Hz。抑制调谐曲线将是 用低水平的主要音调记录，以包括活跃的影响 耳蜗力学和高水平的主要音调，以尽量减少 主动耳蜗力学 调谐曲线宽度、斜率和尖端的测量 将分析年龄、频率和水平差异的特征; 2)在实验2中，DPOAE生长函数（DPOAE振幅作为 初级音调水平）将被生成作为活动耳蜗的测量。 机械或耳蜗放大器活动在人类新生儿在同一时间 发育阶段和f2频率应用于实验1。 DPOAE 生长函数形状、斜率和切迹阈值（振幅平台水平 或减少）将分析年龄和频率差异; 3）在 实验三，以对侧DPOAE抑制为指标 人新生儿内侧橄榄耳蜗传出功能的研究 实验1和2中应用的发育阶段和f2频率。 将在有和没有宽带噪声的情况下记录DPOAE增长函数 传到另一只耳朵。 平均噪音和无噪音的区别 将测试噪声条件以检测对侧DPOAE抑制。 将分析同侧DPOAE抑制的年龄、频率和 水平效应。 除了调查独立开发的 耳蜗调谐，主动耳蜗力学和传出功能，这些 研究将阐明这三个方面之间的关系， 人类成熟过程中的耳蜗生理学。

DESCRIPTION: The long-term goal of this project is to investigate the development of human cochlear function. This understanding will provide a framework for more precise identification of cochlear dysfunction, provide support for development and refinement of auditory prostheses and contribute t general theory on human auditory development. The long-term goal will be accomplished by investigating the timecourse and frequency dependent development of (1) cochlear tuning, (2) active cochlear mechanics, and (3) cochlear efferent function using distortion product otoacoustic emission (DPOAE) methodology. DPOAEs are intermodulation products generated by the normal cochlea when it is presented with two tones (f1, f2) simultaneously. They provide a noninvasive, frequency-specific probe of cochlear physiology in humans. This project includes three experiments: 1) In Experiment 1, DPOAE ipsilateral suppression tuning curves will provide an indirect measure of cochlear tuning in neonates ranging from 29 to 36 weeks conceptional age, term infants and normal-hearing adult subjects at five f2 frequencies: 1100, 2500, 5600, 9000 and 12,500 Hz. Suppression tuning curves will be recorded with low-level primary tones to include influence of active cochlear mechanics, and high-leve primary tones to minimize contribution of active cochlear mechanics. Measures of tuning curve width, slope and tip characteristics will be analyzed for age, frequency, and level differences; 2) In Experiment 2, DPOAE growth functions (DPOAE amplitude as a function of primary tone level) will be generated as a measure of active cochlear mechanics or cochlear amplifier activity in human neonates at the same developmental stages and f2 frequencies applied in Experiment 1. DPOAE growth function shape, slope and notch threshold (level of amplitude plateau or decrease) will be analyzed for age and frequency differences; 3) in Experiment 3, contralateral DPOAE suppression will be measured as an index of medial olivocochlear efferent function in human neonates at the same developmental stages and f2 frequencies applied in Experiments 1 and 2. DPOAE growth functions will be recorded with and without broadband noise presented to the opposite ear. The difference between average noise and no noise conditions will be tested to detect contralateral DPOAE suppression. Contralateral DPOAE suppression will be analyzed for age, frequency and level effects. In addition to investigating the independent development of cochlear tuning, active cochlear mechanics and efferent function, these studies will elucidate the relationship among these three aspects of cochlear physiology during human maturation.