To program a goal-directed response in the presence of acoustic reflections, the audio-motor system should suppress the detection of time-delayed sources. We examined the effects of spatial separation and inter-stimulus delay on the ability of human listeners to localize a pair of broadband sounds in the horizontal plane. Participants indicated how many sounds were heard and where these were perceived by making one or two head-orienting localization responses. Results suggest that perceptual fusion of the two sounds depends on delay and spatial separation. Leading and lagging stimuli in close spatial proximity required longer stimulus delays to be perceptually separated than those further apart. Whenever participants heard one sound, their localization responses for synchronous sounds were oriented to a weighted average of both source locations. For short delays, responses were directed towards the leading stimulus location. Increasing spatial separation enhanced this effect. For longer delays, responses were again directed towards a weighted average. When participants perceived two sounds, the first and the second response were directed to either of the leading and lagging source locations. Perceived locations were interchanged often in their temporal order (in ~40% of trials). We show that the percept of two sounds occurring requires sufficient spatiotemporal separation, after which localization can be performed with high accuracy. We propose that the percept of temporal order of two concurrent sounds results from a different process than localization, and discuss how dynamic lateral excitatory-inhibitory interactions within a spatial sensorimotor map could explain the findings.

中文翻译：

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时空因素影响定位行为中的声源分离

为了在存在声学反射的情况下对目标导向的响应进行编程，音频电机系统应该抑制对时间延迟源的检测。我们研究了空间分离和刺激间延迟对人类听众在水平面上定位一对宽带声音的能力的影响。参与者通过做出一两个面向头部的定位反应来表明听到了多少声音以及在何处感知到这些声音。结果表明，两种声音的感知融合取决于延迟和空间分离。空间接近的超前和滞后刺激需要比距离更远的刺激延迟更长的时间才能在知觉上分开。每当参与者听到一种声音时，他们对同步声音的定位响应都指向两个源位置的加权平均值。对于短暂的延迟，响应指向领先的刺激位置。增加空间分离增强了这种效果。对于更长的延迟，响应再次针对加权平均值。当参与者感知到两个声音时，第一个和第二个响应被定向到领先和落后的源位置。感知位置经常按时间顺序互换（在约 40% 的试验中）。我们表明，对发生的两种声音的感知需要足够的时空分离，然后才能以高精度进行定位。我们提出，两个并发声音的时间顺序感知来自与定位不同的过程，并讨论空间感觉运动图中的动态横向兴奋-抑制相互作用如何解释这些发现。