Masking in the Auditory System

听觉系统的掩蔽

• 批准号: 7846370
• 负责人: TERRY T TAKAHASHI
• 金额: $ 1.86万
• 依托单位: UNIVERSITY OF OREGON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2010-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7846370
• 关键词: Address; Age; Auditory; Auditory system; Barn Owls; Biological Assay; Birds; Brain; Cell Nucleus; Conflict (Psychology); Cues; Data; Discrimination; Ear; Environment; Funding; Head; Hearing; Hearing Aids; Human; Inferior Colliculus; Lead; Location; Maps; Masks; Measures; Midbrain structure; Modeling; Nature; Neurons; Noise; Play; Positioning Attribute; Process; Psychophysiology; Raptors; Relative (related person); Research; Resolution; Role; Self-Help Devices; Signal Transduction; Sound Localization; Source; Stimulus; Stress; Strigiformes; Structure; Techniques; Testing; Time; Tyto alba; base; design; experience; hearing impairment; interest; neuromechanism; neurophysiology; precedence effect; programs; rehabilitation strategy; relating to nervous system; research study; response; sound; sound frequency

DESCRIPTION (provided by applicant): In nature, sounds from an actively-emitting source arrives at the ears slightly before its echo, and this time advantage is thought to play a key role in our ability to perceive the location of the direct sound (localization dominance; LD) and be relatively unaware of the echoes and their points of origin (lag-discrimination suppression; LDS). LD and LDS, collectively known as the "precedence effect", are thought to be the mechanisms by which we segregate acoustical signals of interest from background noise. This process declines with hearing loss and with age, and understanding the neural underpinnings is crucial to the design of assistive devices and rehabilitation strategies. While the fact that the direct sound arrives first is important in the precedence effect, experiments have also shown that signals without a arrival-time difference at the start of the stimulus can still evoke LD. The project proposed is to study LD and LDS in the absence of such onset cues in the barn owl, a nocturnal raptor that can hunt by hearing alone, guided by a map of frontal space in its midbrain. Pilot data suggests that owls, like humans, experience LD even without onset time cues. The project's hypothesis is that LD and LDS are due to consistent lead/lag relationships between the envelope features of the sound pair. Aim 1 Localization Dominance. The hypothesis predicts that without the initial arrival-time difference, the strength of LD will depend on the similarity in the lead and lag envelope structures and the ability to sense the modulations of the envelope. The initial time-advantage is removed from the leading sounds by synchronously gating the sounds, and the envelope similarity and modulation frequencies of the sound pair are manipulated to determine the effect of these factors on LD. LD is assessed using the owl's natural propensity to turn its head in the perceived direction of a sound source. Aim 2 Lag-Discrimination Suppression. Is LDS, the complementary phenomenon to LD, also influenced by the structure of the envelope? The owl's ability to discriminate the position of the lagging source will be investigated using the stimuli used in Aim 1. Discrimination is assessed with a newly developed, non-operant technique for probing the ability of subjects to detect small changes. Aim 3 Neuronal Responses. In Aim 3, we analyze the responses evoked by the synchronously gated stimuli in neurons of the owl's auditory space map. In first experiment, we test whether the suppression of responses to the lagging sound observed with conventional lead/lag stimuli (w/ initial transient disparity & ongoing envelope disparities) are also observable with synchronously gated stimuli. In a second experiment, we test a specific hypothesis about the nature of the suppression in the owl's space map that might allow for the resolution of temporal ambiguities that can arise when the envelope spectra are narrow. PROJECT NARRATIVE In our daily environment, we are able to "hear out" sounds of interest and remain unaware of the echoes that accompany those sounds. Yet, the presence of echoes in a typical acoustical environment is easily witnessed by listening to a playback of a conversation recorded in, e.g., an office. Such soundtracks are often described as "hollow" or "boomy", and these qualities are the result of echoes overlapping with the waves coming directly from the people conversing. Our project will determine how the brain segregates the sound coming directly from the source from the echoes that accompany it. We do so in the barn owl, a bird-of-prey that is especially adept at determining where sounds are coming from and can do so effectively in echo-ridden environments (e.g., barns). This ability to separate the acoustical signal from background noise declines with age and with hearing loss. The findings from our study will therefore help with the design of hearing aids that intelligently extracts of a signal from the background clutter.

描述(申请人提供)：在自然界中，来自主动发射源的声音在回声之前到达耳朵，这一时间优势被认为在我们感知直接声音的位置(局部化优势；LD)以及相对不知道回声及其起源点(滞后歧视抑制；LDS)的能力中起到关键作用。LD和LDS统称为“优先效应”，被认为是我们将感兴趣的声学信号从背景噪声中分离出来的机制。这一过程随着听力损失和年龄的增长而下降，了解神经基础对于辅助设备和康复策略的设计至关重要。虽然直达音最先到达的事实在优先效应中很重要，但实验也表明，在刺激开始时没有到达时间差的信号仍然可以唤起LD。建议的项目是在谷仓猫头鹰缺乏这样的发病线索的情况下研究LD和LDS，谷仓猫头鹰是一种夜间猛禽，可以在中脑额叶空间地图的指导下，仅靠听力捕食。飞行员数据表明，猫头鹰和人类一样，即使在没有发病时间提示的情况下也会经历LD。该项目的假设是，LD和LDS是由于声音对的包络特征之间一致的超前/滞后关系。目标1本土化优势。该假设预测，在没有初始到达时间差的情况下，LD的强度将取决于超前和滞后包络结构的相似性以及感知包络调制的能力。通过同步选通前导声音来消除初始时间优势，并通过操纵声音对的包络相似度和调制频率来确定这些因素对LD的影响。使用猫头鹰将头转向声源感知方向的自然倾向来评估LD。目的2抑制滞后歧视。作为LD的补充现象，LDS是否也受包膜结构的影响？猫头鹰辨别滞后信号源位置的能力将使用AIM 1中使用的刺激进行调查。辨别能力是通过一种新开发的非操作性技术来评估的，该技术用于探测受试者发现微小变化的能力。目的3神经元反应。在目标3中，我们分析了猫头鹰听觉空间图神经元中同步门控刺激引起的反应。在第一个实验中，我们测试了用传统的超前/滞后刺激(初始瞬时视差和持续包络视差)观察到的对滞后声音的反应的抑制是否也可以在同步门控刺激下观察到。在第二个实验中，我们测试了猫头鹰空间地图中关于抑制性质的特定假设，该假设可能允许解决当包络频谱较窄时可能出现的时间模糊性。 项目叙事在我们的日常环境中，我们能够“听到”感兴趣的声音，而不会意识到伴随这些声音的回声。然而，通过收听在例如办公室中记录的对话的回放，可以容易地看到典型声学环境中回声的存在。这样的配乐经常被描述为“空洞的”或“隆隆的”，这些品质是回声与直接从人们交谈中传来的波重叠的结果。我们的项目将确定大脑如何将直接来自来源的声音与伴随它的回声分开。我们在谷仓猫头鹰身上做到了这一点，这是一种猛禽，它特别擅长确定声音来自哪里，并且在回声丰富的环境中(例如谷仓)可以有效地判断声音的来源。这种将声音信号从背景噪音中分离出来的能力随着年龄和听力损失而下降。因此，我们的研究结果将有助于助听器的设计，这种助听器可以智能地从背景杂乱中提取信号。