The Impact of Sensitivity to Fast Spectrotemporal Chirps on Speech Encoding in the Mammalian Inferior Colliculus

哺乳动物听觉中脑对复杂声音特征的敏感性可以为编码提供基础 关键刺激的方案，如语音。最近对兔下丘(IC)的研究揭示了一种新的 对快速光谱啁啾的特征敏感性。单个IC神经元的反应有很大的差异 根据不同的啁啾方向和速度进行调整。这项工作中使用的刺激是施罗德阶段 谐和复数(Schr)，由于其相位特性，在每个基音周期内包含线性调频 谐波分量。由于谐波之间的相位差异，语音必然包含类似的啁啾 声道过滤产生的成分。鉴于IC神经元可能对元音中的啁啾同样敏感 正如它们对Schr啁啾的影响一样，我们假设IC中的新的啁啾敏感性对 在听觉中脑的水平上进行语音编码。这项提议的目标是更准确地界定 这种哺乳动物中枢听觉系统对快速啁啾的敏感度利用生理学实验设计 一种准确反映线性调频灵敏度的IC计算模型，并评估线性调频灵敏度 在语音编码中扮演一个角色。我们将设计新的声音刺激来更多地询问IC的线性调频敏感度 并将啁啾敏感性从其他已知IC特性中分离出来，例如周期性调谐。 计算模型的提出将使用一个基本假设，即对Chirp敏感的IC神经元接收两个或两个或 更多不同频率的输入，并根据输入到达时间做出不同的响应。我们将分析 使用新的分析方法分析语音中包含的啁啾提示。最后，我们将评估线性调频的重要性。 通过比较线性调频敏感和不敏感模型预测语音编码的能力来提高语音编码的灵敏度 生理言语反应。这项工作完成后，将导致对如何 皮层下听觉系统对语音和复杂声音进行编码。这项工作也将是第一批 试图描述和定义这一新的中脑现象。这项提案的结果将有所帮助 确定可用作下一代助听器语音辅助提示的新刺激功能 在嘈杂的环境中理解。拟议的培训计划将集中于提高技能，如 计算神经科学，高级信号处理，数据分析，统计假设检验和 实验设计，完成拟议研究所需的所有技能。培训还将 讲解沟通技巧，如口头和书面陈述，将通过 参加会议和出版期刊出版物。罗切斯特大学代表着一个 理想的位置来完成建议的研究，提供一个方便联系专家的环境 听神经科学和相关领域，以及许多参与职业发展的机会 帮助实现职业目标的活动、研讨会和研讨会。

Sensitivities of the mammalian auditory midbrain to complex sound features can provide the basis for encoding schemes of critical stimuli such as speech. Recent work in rabbit inferior colliculus (IC) has revealed a novel feature sensitivity to fast spectrotemporal chirps. Individual IC neurons had dramatic differences in response rate to differing chirp directions and velocities. The stimulus used in that work was the Schroeder-phase harmonic complex (SCHR), which contains a chirp within each pitch period because of the phase properties of harmonic components. Speech necessarily contains similar chirps due to phase differences between harmonic components resulting from vocal tract filtering. Given that IC neurons may be as sensitive to chirps in vowels as they are to SCHR chirps, we hypothesize that novel chirp sensitivity in the IC significantly contributes to speech coding at the level of the auditory midbrain. The goal of this proposal is to more precisely define this sensitivity in the mammalian central auditory system to fast chirps using physiological experiments, design an IC computational model that accurately reflects chirp sensitivity, and to assess whether chirp sensitivity plays a role in speech coding. We will design novel sound stimuli to interrogate IC chirp sensitivity more directly, and to disentangle chirp sensitivity from other known IC properties, such as periodicity tuning. Computational models will be proposed using a base assumption that chirp-sensitive IC neurons receive two or more inputs of differing frequencies and respond differently depending on input arrival times. We will analyze chirp cues contained in speech using novel analysis methods. Finally, we will evaluate the importance of chirp sensitivity for speech coding by comparing the ability of a chirp-sensitive and -insensitive models to predict physiological speech responses. This work, when completed, will result in a new understanding of how the subcortical auditory system encodes speech and complex sounds. This work will also represent one of the first attempts to characterize and define this novel midbrain phenomenon. The findings of this proposal will help identify new stimulus features that may be used as cues for next-generation hearing aids to assist speech comprehension in noisy environments. The proposed training plan will concentrate on improving skills such as computational neuroscience, advanced signal processing, data analysis, statistical hypothesis testing and experimental design, all skills necessary for the completion of the proposed research. Training will also address communication skills, such as verbal and written presentations, which will be demonstrated by participation in conferences and generation of journal publications. The University of Rochester represents an ideal location to complete the proposed research, providing an environment with easy access to experts in auditory neuroscience and related fields, as well as many opportunities to participate in career-building activities, workshops, and seminars to help reach professional goals.