Forward Masking of Amplitude Modulation

幅度调制的前向掩蔽

• 批准号: 6794296
• 负责人: MAGDALENA WOJTCZAK
• 金额: $ 7.43万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6794296
• 关键词: auditory discrimination; auditory stimulus; auditory threshold; behavioral /social science research tag; clinical research; hearing tests; human subject; neural information processing; perceptual maskings; sensory signal detection; time perception

DESCRIPTION (provided by applicant): The proposed project focuses on the phenomenon of forward masking in the amplitude-modulation (AM) domain. This forward masking refers to a condition in which a well-detectable modulation (signal) is rendered undetectable by adding another modulation (masker) that precedes it in time. Forward masking in the modulation domain may critically affect the perception of speech and other complex stimuli encountered in daily listening situations. The proposed study will be the first to investigate this phenomenon which, because of its temporal characteristics, is different from AM adaptation. The experiments will use times of uninterrupted exposure to AM that are comparable to those present in everyday acoustic stimuli, such as speech. The study will investigate three important characteristics of the forward masking effect: 1) The time course of AM forward masking. The time necessary for the mechanism processing AM to recover to its maximum sensitivity will be estimated by measuring threshold for detecting the signal AM as a function of the delay between the masker and signal AM. 2) Tuning of the effect of AM forward masking. Modulation-rate selectivity of the forward masking effect will be assessed by measuring threshold for detecting the signal AM as a function of the modulation rate of the masker AM. 3) Spectral additivity of AM forward masking. The amounts of forward masking produced by two AM maskers combined together will be compared with the amounts of masking produced by each masker individually. These three experiments will provide information about the temporal and spectral extent to which interfering envelope fluctuations affect the detection of ensuing target fluctuations and about the integration of the effect across modulation rates. The data will establish a foundation for future collaborative work with auditory neurophysiologists with the long-term objective to identify the site and nature of the mechanism underlying AM forward masking and thus to expand knowledge about the mechanisms that process envelope modulations.

描述（由申请人提供）：拟议项目重点研究调幅（AM）域中的前向掩蔽现象。这种前向掩蔽是指这样一种情况：通过及时添加在其之前的另一个调制（掩蔽器），可以很好地检测到的调制（信号）变得不可检测。调制域中的前向掩蔽可能会严重影响日常收听情况下遇到的语音和其他复杂刺激的感知。拟议的研究将是第一个调查这种现象的研究，由于其时间特征，该现象不同于 AM 适应。实验将使用不间断暴露于调幅的时间，该时间与日常声音刺激（例如语音）中的时间相当。该研究将研究前向掩蔽效应的三个重要特征：1）AM前向掩蔽的时间过程。处理AM的机制恢复到其最大灵敏度所需的时间将通过测量用于检测信号AM的阈值来估计，阈值作为掩蔽器和信号AM之间的延迟的函数。 2) 调幅前向掩蔽效果的调整。前向掩蔽效应的调制率选择性将通过测量用于检测作为掩蔽AM的调制率的函数的信号AM的阈值来评估。 3）AM前向掩蔽的频谱可加性。将两个 AM 掩蔽器组合在一起产生的前向掩蔽量与每个掩蔽器单独产生的掩蔽量进行比较。这三个实验将提供有关干扰包络波动影响后续目标波动检测的时间和频谱范围的信息，以及有关跨调制速率的影响积分的信息。这些数据将为未来与听觉神经生理学家的合作奠定基础，其长期目标是确定 AM 前向掩蔽机制的位点和性质，从而扩展有关处理包络调制机制的知识。