Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA.
J Neurosci. 2010 Jun 9;30(23):7826-37. doi: 10.1523/JNEUROSCI.5517-09.2010.
In reverberant environments, acoustic reflections interfere with the direct sound arriving at a listener's ears, distorting the binaural cues for sound localization. We investigated the effects of reverberation on the directional sensitivity of single neurons in the inferior colliculus (IC) of unanesthetized rabbits. We find that reverberation degrades the directional sensitivity of single neurons, although the amount of degradation depends on the characteristic frequency (CF) and the type of binaural cues available. When interaural time differences (ITDs) are the only available directional cue, low-CF cells sensitive to ITDs in the waveform fine time structure maintain better directional sensitivity in reverberation than high-CF cells sensitive to ITDs in the envelope induced by cochlear filtering. Conversely, when both ITD and interaural level difference (ILD) cues are available, directional sensitivity in reverberation is comparable throughout the tonotopic axis of the IC. This result suggests that, at high frequencies, ILDs provide better directional information than envelope ITDs, emphasizing the importance of the ILD-processing pathway for sound localization in reverberation.
在混响环境中，声音反射会干扰到达听众耳朵的直达声，从而改变声音定位的双耳线索。我们研究了混响对未麻醉兔下丘脑中单个神经元方向敏感性的影响。我们发现混响会降低单个神经元的方向敏感性，尽管这种退化程度取决于特征频率 (CF) 和可用的双耳线索类型。当仅使用两耳时间差 (ITD) 作为方向线索时，对波形精细时间结构中 ITD 敏感的低 CF 细胞在混响中比对耳蜗滤波引起的包络中 ITD 敏感的高 CF 细胞保持更好的方向敏感性。相反，当同时存在 ITD 和两耳强度差 (ILD) 线索时，混响中的方向敏感性在整个 IC 的音调轴上是可比的。这一结果表明，在高频时，ILD 比包络 ITD 提供更好的方向信息，强调了 ILD 处理途径在混响中声音定位的重要性。
