Masking in the Auditory System

听觉系统的掩蔽

• 批准号: 7576112
• 负责人: TERRY T TAKAHASHI
• 金额: $ 32.35万
• 依托单位: UNIVERSITY OF OREGON
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7576112
• 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.

描述（由申请人提供）：在自然界中，来自主动发射源的声音在其回声之前到达耳朵，并且这种时间优势被认为在我们感知直达声音的位置（定位优势；LD）以及相对不知道回声及其起源点（滞后辨别抑制；LDS）的能力中发挥着关键作用。 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与背景噪声分离的机制。这一过程随着听力损失和年龄的增长而减弱，了解神经基础对于辅助设备和康复策略的设计至关重要。虽然直达声首先到达这一事实对于优先效应很重要，但实验还表明，在刺激开始时没有到达时间差的信号仍然可以引起 LD。拟议的项目是在谷仓猫头鹰没有此类起始线索的情况下研究 LD 和 LDS。谷仓猫头鹰是一种夜间活动的猛禽，可以在中脑额叶空间图的引导下仅靠听觉进行捕猎。试点数据表明，猫头鹰和人类一样，即使没有发病时间提示也会经历 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/滞后关系造成的。目标 1 本地化主导地位。该假设预测，如果没有初始到达时间差异，LD 的强度将取决于超前和滞后包络结构的相似性以及感测包络调制的能力。通过同步选通声音，从主导声音中消除初始时间优势，并操纵声音对的包络相似性和调制频率来确定这些因素对 LD 的影响。 LD 是利用猫头鹰将头转向感知到的声源方向的自然倾向来评估的。目标 2 滞后歧视抑制。 LDS（LD 的互补现象）是否也受到包络结构的影响？将使用目标 1 中使用的刺激来研究猫头鹰区分滞后源位置的能力。使用新开发的非操作技术来评估区分能力，以探测受试者检测微小变化的能力。目标 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，我们测试了用传统超前/滞后刺激（带有初始瞬态差异和持续包络差异）观察到的对滞后声音的响应的抑制是否也可以用同步门控刺激观察到。在第二个实验中，我们测试了关于猫头鹰空间图中抑制性质的特定假设，该假设可能允许解决当包络谱很窄时可能出现的时间模糊性。