Buildup and Breakdown of Precedence in ITD and ILD

ITD 和 ILD 优先级的建立和分解

• 批准号: 8142121
• 负责人: Andrew Dennis Brown
• 金额: $ 3.25万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-16 至 2012-08-18
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8142121
• 关键词: Accounting; Acoustics; Auditory; Auditory system; Awareness; Bilateral; Brain Stem; Clinical; Cochlear Implants; Communication; Complex; Cues; Data; Ear; Employee Strikes; Environment; Faculty; Goals; Hearing; Image; Individual; Judgment; Literature; Location; Maintenance; Measures; Mediating; Mission; National Institute on Deafness and Other Communication Disorders; Population; Procedures; Process; Psychophysiology; Recovery; Research; Role; Signal Transduction; Sound Localization; Source; Stimulus; Testing; Time; Work; insight; precedence effect; public health relevance; research study; sound; virtual

DESCRIPTION (provided by applicant): The ability to localize sound is integral to communication and environmental awareness. Normal hearing listeners localize sound in the horizontal plane by responding to interaural differences in signal timing (ITD) and level (ILD) at the two ears. In ordinary listening environments (e.g., rooms), accurate localization requires that listeners respond to the cues carried by the early-arriving incident sound rather than the spurious cues carried by later-arriving reflected sound. In fact, localization by normal hearing listeners is remarkably unaffected by echoes and reverberation. The various phenomena associated with this observation are known collectively as the precedence effect. Although the adaptive value of the precedence effect in sound localization is clear, important questions about the effect remain. For example, although ITD and ILD are distinct acoustic cues, thought to be processed separately in the auditory brainstem, most precedence findings reflect data from studies employing headphone ITD or free field stimuli where the contributions of ITD and ILD to localization judgments are inseparable: relatively little is known about the contribution of ILD to precedence, despite evidence that ILD is the dominant cue in localization for some listeners, including a growing population of bilateral cochlear implant users. Thus, the broad long-term goal of the proposed research is to elucidate the separate contributions of ITD and ILD to the precedence effect in order to establish a more complete and clinically informative account of sound localization in ordinary listening environments. The specific aims of the proposed research are (1) to examine listeners' sensitivity to "echoes" following repeated presentations of "source-echo" stimuli carrying only ITD or ILD and (2) to examine listeners' sensitivity to "echoes" following repeated presentations of "source-echo" stimuli carrying combinations of ITD and ILD. Recent data from the Applicant's lab suggests that the time course of ITD sensitivity is substantially different from the time course of ILD sensitivity. Thus, toward the first aim, an initial experiment will test the hypothesis that echo suppression is more robust for stimuli carrying ITD than for stimuli carrying ILD. Toward the second aim, an additional experiment will test the hypothesis that "dynamic" echo suppression depends on sensitivity to both ITD and ILD "images." Across experiments, stimuli will be presented via headphones to allow for independent manipulation of ITD and ILD cues, and echo thresholds will be estimated by an adaptive psychophysical procedure. The proposed research will provide valuable new insight on a large body of existing precedence effect literature and on the unique roles of ITD and ILD in spatial hearing. The work will thus inform both basic and clinical understanding of audition, underscoring this proposal's relevance to the mission of NIDCD. PUBLIC HEALTH RELEVANCE: The ability to determine where sounds are coming from is an important part of hearing. Although everyday listening environments introduce echoes and reverberation that might be expected to make it very difficult to determine the location of actual sound sources, normal hearing listeners are remarkably capable of accurate localization under such conditions. The proposed research builds on what is known about this capacity to expand basic understanding of sound localization and to provide insight on the reduced sound localization abilities of certain hearing impaired populations, including bilateral cochlear implant users.

描述（由申请人提供）：定位声音的能力是沟通和环境意识不可或缺的一部分。正常听力的听者通过对两耳信号时序（ITD）和电平（ILD）的耳间差异作出反应，将声音定位在水平面上。在普通的听音环境中（如房间），准确的定位要求听者对早到的偶发声音所携带的线索作出反应，而不是对晚到的反射声音所携带的虚假线索作出反应。事实上，正常听力的听众的定位明显不受回声和混响的影响。与这种观察有关的各种现象统称为优先效应。虽然优先效应在声音定位中的自适应价值是明确的，但关于优先效应的重要问题仍然存在。例如，虽然ITD和ILD是不同的声音线索，被认为是在听觉脑干中分别处理的，但大多数优先发现反映的是使用耳机ITD或自由场刺激的研究数据，其中ITD和ILD对定位判断的贡献是不可分割的：尽管有证据表明ILD是一些听者定位的主要线索，包括越来越多的双侧人工耳蜗使用者，但对于ILD对优先级的贡献知之甚少。因此，本研究的长期目标是阐明ITD和ILD对优先效应的单独贡献，以便在普通听力环境中建立更完整和临床信息的声音定位描述。所提出的研究的具体目的是：(1)检查听者在反复呈现仅携带ITD或ILD的“源回声”刺激后对“回声”的敏感性；(2)检查听者在反复呈现携带ITD和ILD组合的“源回声”刺激后对“回声”的敏感性。申请人实验室的最新数据表明，过渡段敏感性的时间过程与ILD敏感性的时间过程有很大不同。因此，为了实现第一个目标，一个初步的实验将检验这一假设，即携带ITD的刺激比携带ILD的刺激对回声的抑制更强。为了实现第二个目标，一个额外的实验将测试“动态”回波抑制取决于对过渡段和过渡段“图像”的灵敏度的假设。在整个实验中，刺激将通过耳机呈现，以允许独立操作ITD和ILD线索，回声阈值将通过自适应心理物理程序估计。该研究将为大量现有的优先效应文献以及过渡段和ILD在空间听力中的独特作用提供有价值的新见解。因此，这项工作将为听力的基本和临床理解提供信息，强调本建议与NIDCD使命的相关性。