Auditory neural coding of speech

项目总结/摘要 日常收听环境通常包括噪声和声学反射离开周围表面，这些噪声和声学反射一起被称为 作为混响。听力正常的人在这样的环境中可以毫不费力地匡威， 失去他们是一种挑战。尽管混响无处不在，但人们对鲁棒性的神经机制知之甚少。 听混响，甚至更少是已知的噪声和混响对神经元的综合影响， 编码拟议的研究将首次调查类似语音的刺激如何在现实中呈现， 在未麻醉的兔子模型的听觉中脑中编码混响。听觉中脑 在优先效应中起关键作用，有助于混响中准确的声音定位。三个具体目标 将使用越来越现实的刺激来解决基本问题。因为振幅包络的调制 对于语音接收是必不可少的，具体目标1将侧重于调幅（AM）刺激。我们将测试 假设在AM声音的时间编码中出现先前识别的“混响优势”， 神经元对AM的敏感性通过它们对耳间相干性波动的敏感性而增强， 伴随着AM的回响。如果得到证实，这一假设将突出保持动态的重要性。 助听器的选配具体目标2将直接测试自然语音是如何由中脑听觉神经元编码的 不同程度的混响。我们将使用现代技术从神经群体中重建刺激 活动，以定量评估混响中神经编码的鲁棒性，并测试是否适应 混响环境的统计有助于鲁棒编码。具体目标3将扩展目标2的结果， 当混响与背景噪声结合时的常见情况。使用创新技术， 独立控制混响的数量在语音目标和噪声干扰，我们将解开如何 目标的神经编码受到每一个的影响。我们将确定如何在降解双耳 由混响引起的提示降低了目标和接收者之间的空间分离对于神经编码的益处 目标的位置总之，这些研究将增加对神经机制的基本理解， 混响中的神经编码研究结果将指导助听器新处理策略的开发 以及人工耳蜗，可以改善日常环境中的语言接收能力。

Project Summary/Abstract Everyday listening environments often comprise noise and acoustic reflections off surrounding surfaces, together known as reverberation. While normal-hearing listeners can converse in such environments with little effort, those with hearing loss find them challenging. Despite the ubiquity of reverberation, little is known about the neural mechanisms for robust listening in reverberation and even less is known about the combined effects of noise and reverberation on neural coding. The proposed studies will, for the first time, investigate how speech-like stimuli presented in realistic reverberation are encoded in the auditory midbrain of an unanesthetized rabbit model. The auditory midbrain is known to play a key role in the precedence effect, which helps accurate sound localization in reverberation. Three specific aims will use stimuli of increasing realism to address fundamental questions. Because modulations of the amplitude envelope are essential for speech reception, Specific Aim 1 will focus on amplitude modulated (AM) stimuli. We will test the hypothesis that a previously identified “reverberant advantage” in the temporal coding of AM sounds occurs because the neurons sensitivity to AM is enhanced by their sensitivity to the fluctuations in interaural coherence that necessarily accompany AM in reverberation. If verified, this hypothesis would highlight the importance of preserving dynamic binaural cues in hearing aids. Specific Aim 2 will directly test how natural speech is coded by midbrain auditory neurons in various amounts of reverberation. We will use modern techniques for stimulus reconstruction from neural population activity to quantitatively assess the robustness of neural coding in reverberation and test whether adaptation to the statistics of the reverberant environment contributes to robust coding. Specific Aim 3 will extend the Aim 2 results to the common case when reverberation is combined with background noise. Using an innovative technique to independently control the amount of reverberation in a speech target and a noise interferer, we will disentangle how the neural coding of the target is affected by each. We will determine how the degradation in the interferer binaural cues caused by reverberation reduces the benefit of spatial separation between target and interferer for neural coding of the target. Together, these studies will increase fundamental understanding of the neural mechanisms for robust neural coding in reverberation. The findings will guide the development of new processing strategies for hearing aids and cochlear implants that would improve speech reception in everyday challenging environments.