Devore Sasha, Ihlefeld Antje, Hancock Kenneth, Shinn-Cunningham Barbara, Delgutte Bertrand
Eaton Peabody Laboratory, Massachusetts Eye & Ear Infirmary, Boston, MA 02114, USA.
Neuron. 2009 Apr 16;62(1):123-34. doi: 10.1016/j.neuron.2009.02.018.
In reverberant environments, acoustic reflections interfere with the direct sound arriving at a listener's ears, distorting the spatial cues for sound localization. Yet, human listeners have little difficulty localizing sounds in most settings. Because reverberant energy builds up over time, the source location is represented relatively faithfully during the early portion of a sound, but this representation becomes increasingly degraded later in the stimulus. We show that the directional sensitivity of single neurons in the auditory midbrain of anesthetized cats follows a similar time course, although onset dominance in temporal response patterns results in more robust directional sensitivity than expected, suggesting a simple mechanism for improving directional sensitivity in reverberation. In parallel behavioral experiments, we demonstrate that human lateralization judgments are consistent with predictions from a population rate model decoding the observed midbrain responses, suggesting a subcortical origin for robust sound localization in reverberant environments.
在混响环境中,声学反射会干扰到达听众耳朵的直达声,从而扭曲声音定位的空间线索。然而,人类听众在大多数环境中进行声音定位几乎没有困难。由于混响能量会随着时间积累,声源位置在声音的早期部分相对忠实地呈现出来,但在刺激后期这种呈现会逐渐退化。我们发现,麻醉猫的听觉中脑单个神经元的方向敏感性遵循类似的时间进程,尽管时间响应模式中的起始优势导致方向敏感性比预期更强,这表明存在一种在混响中提高方向敏感性的简单机制。在并行的行为实验中,我们证明人类的侧向化判断与从解码观察到的中脑反应的群体速率模型得出的预测一致,这表明在混响环境中进行稳健声音定位的起源是皮层下的。