The role of envelope shape in the localization of multiple sound sources and echoes in the barn owl
The role of envelope shape in the localization of multiple sound sources and echoes in the barn owl
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DOI：
10.1152/jn.00755.2012
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发表时间：
2013-02-01
影响因子：
2.5
通讯作者：
Takahashi, Terry T.
中科院分区：
文献类型：
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作者：
Baxter, Caitlin S.;Nelson, Brian S.;Takahashi, Terry T.
Baxter CS, Nelson BS, Takahashi TT。包络形状在仓鸮多声源和回声定位中的作用。中国生物医学工程学报（英文版），2009；首次发表于2012年11月21日；doi: 10.1152 / jn.00755.2012。回声和独立来源的声音通常会模糊感兴趣的声音，但回声在自然听力条件下无法被检测到，这种感知称为优先效应。听觉系统如何区分回声和独立声源？为了进行研究，我们向仓鸮（Tyto alba）提供了两种宽带噪声，同时改变了声音信封的相似性。除了2或3毫秒的延迟外，噪音的载体是相同的。它们的起跳和偏移也是同步的。猫头鹰的声音定位是由听觉空间地形图上的神经活动引导的。当有两个声源同时发出具有重叠振幅谱的声音时，空间图神经元在其感受野内的刺激比外界的刺激大，且两种声音的平均振幅都在上升时放电。结合这些特征的模型计算了两个来源在地图上表示的强度（B. S. Nelson和T. T. Takahashi; Neuron 67: 643-655, 2010）。猫头鹰定位的目标可以从模型的输出中预测出来。该模型还解释了为什么回声在短延迟时不被定位：当包络相似时，领先声掩模的峰值与回声的峰值相对应，削弱了回声的空间图表示。当包络不相同时，对应的峰值很少或没有，猫头鹰将模型预测的源定位为较少被掩盖的源。因此，猫头鹰的优先效应是在其地图上表示多个声源的机制的副产品。
Baxter CS, Nelson BS, Takahashi TT. The role of envelope shape in the localization of multiple sound sources and echoes in the barn owl. J Neurophysiol 109: 924-931, 2013. First published November 21, 2012; doi:10.1152/jn.00755.2012.-Echoes and sounds of independent origin often obscure sounds of interest, but echoes can go undetected under natural listening conditions, a perception called the precedence effect. How does the auditory system distinguish between echoes and independent sources? To investigate, we presented two broadband noises to barn owls (Tyto alba) while varying the similarity of the sounds' envelopes. The carriers of the noises were identical except for a 2- or 3-ms delay. Their onsets and offsets were also synchronized. In owls, sound localization is guided by neural activity on a topographic map of auditory space. When there are two sources concomitantly emitting sounds with overlapping amplitude spectra, space map neurons discharge when the stimulus in their receptive field is louder than the one outside it and when the averaged amplitudes of both sounds are rising. A model incorporating these features calculated the strengths of the two sources' representations on the map (B. S. Nelson and T. T. Takahashi; Neuron 67: 643-655, 2010). The target localized by the owls could be predicted from the model's output. The model also explained why the echo is not localized at short delays: when envelopes are similar, peaks in the leading sound mask corresponding peaks in the echo, weakening the echo's space map representation. When the envelopes are dissimilar, there are few or no corresponding peaks, and the owl localizes whichever source is predicted by the model to be less masked. Thus the precedence effect in the owl is a by-product of a mechanism for representing multiple sound sources on its map.