STUDIES OF HUMAN SOUND LOCALIZATION

对于许多生物体来说，声音定位是一个关乎生存的问题。为 人类，这样的说法可能有些言过其实。然而，不可能有 否认声音本土化在人类生活中的重要性。它从属于 我们能够在嘈杂的环境中分离目标消息和竞争消息 环境，这是正常交流的重要组成部分。 当这种能力退化时，就像许多类型的听力损失一样， 通讯严重中断。这样做的长期目标是 项目是对以下方面的机制和过程的完整理解 人声定位。广泛的研究表明，明显的 声音的位置由三个主要声学提示确定： 耳间时差、耳间水平差和耳廓 过滤效果。在某些情况下，一个或多个 提示可能是模棱两可或不可靠的，例如收听窄带 声音或不熟悉的声音。在这些情况下，监听器必须使用 其他线索或对主要线索进行不同的加权。的主要关注点 这个项目是额外线索的提取和使用，以及 可供选择的权重策略。具体来说，该项目将 研究从小头运动中获得的定位线索的使用 以及听众对具体情况的了解或期望的作用 刺激特征。在拟议的实验中，人类听众 将估计在一个免费的 通过传送计算机产生的声场或虚拟自由场- 通过耳机合成声音。在虚拟自由场中，头部位置 用磁性跟踪器监测，这样刺激就可以 实时进行适当修改。听者对或的知识 对刺激的预期是通过改变之间的- 刺激频谱的刺激和刺激内方差。其他内容 实证研究将调查支配经济增长的刺激因素 单个声源在听觉空间中的可分性。在这些后者中 实验中，听者将指出两个明显的位置 虚拟自由场中的独立信号源。刺激参数，如 幅度包络相干性、起始偏移量异步性和频谱 重叠部分将被处理以评估它们对成功的重要性 源头隔离。除了经验性工作外，该项目还将 对声音定位的神经网络模型进行评估。该模型是一种 基于径向基的单隐层、单输出层网络 功能架构。神经网络模型很有吸引力，因为 训练和学习，这被认为对人类的声音很重要 本地化，明确包含在模型中。

For many organisms sound localization is a matter of survival. For humans, such a claim would be an overstatement. However, there can be no denying the importance of sound localization in human life. It subserves our ability to segregate target and competing messages in noisy environments, which is an essential component of normal communication. When that ability is degraded, as with many types of hearing loss, communication is significantly disrupted. The long-term goal of this project is a complete understanding of the mechanisms and processes of human sound localization. Extensive research suggests that the apparent position of a sound is determined by three primary acoustical cues: interaural time differences, interaural level differences, and pinna filtering effects. There are circumstances in which one or more of the cues may be ambiguous or unreliable, such as listening to a narrowband sound or to an unfamiliar sound. In these cases listeners must either use additional cues or weight the primary cues differently. A major focus of this project is the extraction and use of the additional cues, and the alternative weighting strategies. Specifically, the project will investigate the use of localization cues derived from small head movements and the role of a listener's knowledge of or expectations about specific stimulus characteristics. In the proposed experiments human listeners will estimate the apparent positions of sounds presented in either a free sound field or the virtual free-field produced by delivering computer- synthesized sound over headphones. In virtual free-field, head position is monitored with a magnetic tracker so that the stimuli can be appropriately modified in real time. A listener's knowledge of or expectations about the stimuli is manipulated by changing the between- stimuli and within-stimulus variance of the stimulus spectrum. Additional empirical studies will investigate the stimulus features that govern the separability of individual sources in auditory space. In these latter experiments, listeners will indicate the apparent positions of two independent sources in a virtual free-field. Stimulus parameters such amplitude envelope coherence, onset-offset asynchrony, and spectral overlap will be manipulated to assess their importance for successful source segregation. In addition to the empirical work, the project will evaluate a neural network model of sound localization. The model is a single hidden-layer, single output layer network based on a radial basis function architecture. Neural network models are attractive since training and learning, which are thought to be important in human sound localization, are explicitly incorporated in the models.