INNER EAR, CENTRAL CONTROL--OLIVOCOCHLEAR REFLEX IN HUMANS

这个项目的总体目标是了解如何自然如何 包括混响的自然声学环境， 在听觉中脑中表示多个声源。 如此复杂的环境，在每一个... 天的情况下，沙子造成的讲话接收困难， 听力受损我们将使用强大的~虚拟空间~ 我们在前面的项目中开发的刺激技术 期 这项技术，它模拟自然的声音， 封闭的声学系统，实现精确的 对用于声音定位的单个声学线索的控制 （时间和水平以及频谱的壁间差异）。这 技术将用于研究神经机制， 听众更好地检测声音信号在嘈杂的背景时， 信号和噪声在空间上分离（目标1）。 我们将 评估单耳和双耳因素的玫瑰的能力， 神经细胞群来检测信号， 噪声，并确定哪些定位线索是最重要的， 侦测 我们还将研究神经相关的优先级， 效果，其中听众准确地定位声源在 存在来自墙壁表面的反射（目标2）。 我们将测试 关于大脑前丘神经元群体 通过比较声音位置的估计来表示声音位置 从神经反应中得到的， 在反射存在下的人类定位判断。 到 更好地理解定位机制的解剖学基础， 我们将把神经元的生理特性 空间听觉到他们的位置相对于区域，显示 独特的细胞化学标记（Aim 3）。 这项工作涉及一般 关于空间听觉的神经基础的问题：听觉如何 空间是在神经群体中表示的，听觉是如何 系统利用位置的差异来区分和识别 听觉对象，它如何处理反射和竞争 以及这些神经机制 具体取决于方向信息。 组合 随着对语音神经编码的研究，这项工作可能 澄清为什么听力受损和老年听众有更大的 比正常人在在场的情况下理解言语的困难 混响和竞争的声音，并可能有助于开发新的 助听器的种类，将在嘈杂和 混响环境。

The overall goal of this project is to understand how natural how natural acoustic environments that include reverberations and multiple sound sources are represented in the auditory midbrain. Such complex environments are frequently encountered in every- day situation, sand cause difficulties in speech reception for the hearing-impaired. We will use the powerful ~virtual-space~ stimulation technique that we developed in the preceding project period. This technique, which simulates natural acoustic environments with closed acoustic systems, achieves precise control over individual acoustic cues used for sound localization (intermural differences in time and level, and spectrum). This technique will be used to study neural mechanisms that allow listeners to better detect sound signals in noisy backgrounds when the signal and the noise are spatially separated (Aim 1). We will assess the roses of monaural and binaural factors in the ability of populations of inferior-colliculus neurons to detect the signal in noise, and identify which localization cues are most important for detection. We will also study neural correlates of the precedence effect, wherein listeners accurately localize sound sources in the presence of reflections from wall surfaces (Aim 2). We will test hypotheses as to how populations of inferior-colliculus neurons represent sound location by comparing estimates of sound location derived from neural responses with corresponding patterns of human localization judgements in the presence of reflections. To better understand the anatomical basis of localization mechanisms, we will correlate physiological properties of neurons important for spatial hearing to their location with respect to regions that show distinct cytochemical labels (Aim 3). This work addresses general questions about the neural basis of spatial hearing: how auditory space is represented in neural populations, how the auditory system uses differences in location to separate and recognize auditory objects, how it copes with reflections and competing sounds, and the extent to which these neural mechanisms specifically depend on directional information. In combination with research on the neural coding of speech, this work may clarify why hearing-impaired and elderly listeners have greater difficulties than normals in understanding speech in the presence of reverberation and competing sounds, and may help develop new kinds of hearing aids that would perform better in noisy and reverberant environments.