Complex Pitch Perception in Complex Environments

描述(申请人提供)：这个项目的长期目标是加深我们对听觉系统如何形成音调感知以及如何使用音调或基频来区分来自不同来源的声音的理解。该项目有三个主要目标，都是将心理物理实验与计算建模相结合。第一个目的是阐明在听力正常和受损的情况下，单谐复杂声音的基音是如何编码的。我们假设，可分辨谐波的减少，加上单个谐波编码精度的降低，可以预测在更复杂的声学环境中听力受损的听者所经历的许多困难。第二个目标是继续寻找我们感知多个音高并在其他竞争复合体存在的情况下听到一个音高的能力的机制。通过仔细研究刺激在光谱上完全重叠或根本不重叠的受控情况，我们能够控制复合体中单个谐波被分解的程度。这些情况可以作为更复杂情况的模型，在这些情况下，多个部分重叠的声音组合在一起形成了我们的日常声学环境。第三个目标采取了更实用的方法，考察了音高和基频在言语和音乐感知中的作用。我们将利用人工耳蜗植入过程的模拟，阐明在残留听力(声电刺激)条件下提供益处的机制，并评估这种益处可以归因于改善音调信息的程度。我们还将开始系统地分析日常声学环境中存在(或不存在)可分解的谐波，例如在竞争说话者在场的情况下的语音和小型合奏中的音乐。这些分析的数据将为复杂的音调感知模型提供强有力的约束，这些模型在不同程度上依赖于已分解的谐波的存在。了解在正常和受损的听觉系统中基音是如何被编码和利用的，对于设计和开发听觉假体，例如人工耳蜗，以及自动语音识别系统中的源分离算法具有重要的意义。

DESCRIPTION (provided by applicant): The long-term goal of this project is to further our understanding of how the auditory system forms pitch percepts and how pitch or fundamental frequency is used to separate sounds coming from different sources. The project has 3 main aims, all of which combine psychophysical experiments with computational modeling. The first aim is to elucidate how the pitch of single harmonic complex sounds is coded in normal and impaired hearing. We hypothesize that the reduced availability of resolved harmonics, in conjunction with a reduction in the coding accuracy of individual harmonics, can predict many difficulties experienced by hearing-impaired listeners in more complex acoustic environments. The second aim is to continue our search for the mechanisms underlying our ability to perceive multiple pitches and to hear out 1 pitch in the presence of other competing complexes. By studying carefully controlled situations where the stimuli either completely overlap in spectrum or do not overlap at all, we are able to control the degree to which individual harmonics within the complexes are resolved. These situations serve as models for the more complex situations, where multiple partially-overlapping sounds combine to form our everyday acoustic environment. The third aim takes a more applied approach by examining the role of pitch and fundamental frequency in speech and music perception. Using simulations of cochlear-implant processing we will elucidate the mechanisms involved in providing a benefit under conditions of residual hearing (acoustic plus electric stimulation) and assess the degree to which the benefit can be ascribed to improved pitch information. We will also begin a systematic analysis of the presence (or lack thereof) of resolved harmonics in everyday acoustic situations, such as speech in the presence of competing talkers and music in small ensembles. The data from these analyses will provide strong constraints for models of complex pitch perception that rely to varying degrees on the presence of resolved harmonics. Understanding how pitch is coded and utilized in the normal and impaired auditory system should have important implications for the design and development of auditory prostheses, such as cochlear implants, and for source segregation algorithms within automatic speech recognition systems.