Complex Pitch Perception in Complex Environments

音高在听觉和言语感知中起着重要的作用。它定义了音乐中的旋律与和声， 它为语音提供韵律和（在声调语言中）词汇信息;它在以下方面起着至关重要的作用： 我们分离和跟踪竞争声源的能力。尽管它的重要性，许多基本方面， 音高处理和感知仍然是未知的。例如，虽然听力损失通常会降低音调， 虽然人们对这一概念的认识不同，但对潜在机制却没有达成一致意见。此外，尽管耳蜗植入物 许多成功涉及语音感知，但音高仍然表现得很差。这些赤字可能有助于 解释听力损失和人工耳蜗植入者在听演讲时遇到的困难， 复杂的声学环境。这个项目的长期目标是提高我们对 正常人和受损人对单个和并发声音的音高感知机制 听觉系统该提案分为三个具体目标。第一个目标使用感知措施， 测试关于纯音和复音的音高编码的重要假设。 在第一个实验中，个体差异研究的新应用被用来检验假设 衰老和耳蜗性听力损失通过不同的机制， 音高感知的退化。第二个实验解决了多个音高是如何 在正常听力条件下编码。第三和第四个实验分别测试了模拟和真实的耳蜗- 植入用户，分别探测光谱分辨率的限制，以提取复杂的音高， 未来几代的植入物，并测试在何种程度上目前的植入物可以传输多个间距 同步第二个目标涉及三项高场（7特斯拉）功能磁成像（fMRI）研究。 一项研究提供了第一个测试tonotopy到非常高的频率，以测试假设， 高频感知反映的是皮层而不是外围编码限制。另一项研究试图 通过分离基频和频谱质心来分离音高和音色的表示。 第三项研究解决了一个潜在的刺激混淆，涉及光谱稀疏，可能会影响 先前试图在听觉皮层内定位“音高中心”的尝试。第三个目标是大规模的 研究音乐和音高训练对与音乐直接相关的技能（如音高）的影响 辨别力，或者更普遍的，例如在噪音中理解语音的能力。早期的研究 在这个重要的问题上得出了不同的结论，部分原因是样本量相对较小 测试.一项大规模的相关性研究，涉及比较知觉和生理措施， 有或没有长期音乐训练的人，和一个大规模的随机对照研究， 在成人中进行音高辨别训练的效果将为这些重要问题提供更明确的答案。 问题.

Pitch plays a fundamental role in auditory and speech perception. It defines melody and harmony in music; it contributes both prosodic and (in tone languages) lexical information to speech; and it plays a crucial role in our ability to segregate and follow competing sound sources. Despite its importance, many basic aspects of pitch processing and perception remain unknown. For instance, although hearing loss often degrades pitch perception, there is little agreement as to the underlying mechanisms. In addition, despite cochlear-implants’ many successes involving speech perception, pitch remains very poorly represented. These deficits may help explain the difficulties people with hearing loss and cochlear implants experience when listening to speech in complex acoustic environments. The long-term goal of this project is to improve our understanding of the mechanisms underlying the perception of pitch of single and concurrent sounds in the normal and impaired auditory systems. The proposal is divided into three specific aims. The first aim uses perceptual measures to test important hypotheses regarding the coding of pitch of pure and complex tones in isolation and in mixtures. In the first experiment, novel applications of studies of individual differences are used to test the hypothesis that ageing and cochlear hearing loss contribute independently and via different mechanisms to the degradation of pitch perception. The second experiment addresses questions of how multiple pitches are coded under normal-hearing conditions. The third and fourth experiments test simulated and real cochlear- implant users, respectively, to probe the limits of spectral resolution necessary to extract complex pitch in future generations of implants, and to test the extent to which current implants can transmit multiple pitches simultaneously. The second aim involves three high-field (7 Tesla) functional magnetic imaging (fMRI) studies. One study provides the first test of tonotopy up to very high frequencies, to test the hypothesis that poorer pitch perception at high frequencies reflects cortical rather than peripheral coding limitations. Another study attempts to separate representations of pitch from timbre by dissociating fundamental frequency and spectral centroid. The third study addresses a potential stimulus confound involving spectral sparsity that may have influenced previous attempts to locate a “pitch center” within the auditory cortex. The third aim proposes a large-scale study of the effects of musical and pitch training on skills that are either directly related to music, such as pitch discrimination, or are more general, such as the ability to understand speech in noise. Earlier studies have reached mixed conclusions on this important question, in part because of the relatively small sample sizes tested. One large-scale correlational study involving a comparison of perceptual and physiological measures in people with or without long-term musical training, and one large-scale randomized controlled study of the effects of pitch-discrimination training in adults will provide more definitive answers to these important questions.