Kan Alan, Jones Heath G, Litovsky Ruth Y
Binaural Hearing and Speech Laboratory, Waisman Center, University of Wisconsin-Madison, 1500 Highland Avenue, Madison, Wisconsin 53705, USA.
J Acoust Soc Am. 2015 Dec;138(6):3826-33. doi: 10.1121/1.4937754.
Recent psychophysical studies in bilateral cochlear implant users have shown that interaural timing difference (ITD) sensitivity with electrical stimulation varies depending on the place of stimulation along the cochlear array. While these studies have measured ITD sensitivity at single electrode places separately, it is important to understand how ITD sensitivity is affected when multiple electrodes are stimulated together because multi-electrode stimulation is required for representation of complex sounds. Multi-electrode stimulation may lead to poorer overall performance due to interference from places with poor ITD sensitivity, or from channel interaction due to electrical current spread. Alternatively, multi-electrode stimulation might result in overall good sensitivity if listeners can extract the most reliable ITD cues available. ITD just noticeable differences (JNDs) were measured for different multi-electrode configurations. Results showed that multi-electrode ITD JNDs were poorer than ITD JNDs for the best single-electrode pair. However, presenting ITD information along the whole array appeared to produce better sensitivity compared with restricting stimulation to the ends of the array, where ITD JNDs were comparable to the poorest single-electrode pair. These findings suggest that presenting ITDs in one cochlear region only may not be optimal for maximizing ITD sensitivity in multi-electrode stimulation.
近期针对双侧人工耳蜗使用者的心理物理学研究表明，电刺激下的双耳时间差（ITD）敏感度会因沿耳蜗阵列的刺激位置不同而有所变化。虽然这些研究分别测量了单个电极位置的ITD敏感度，但了解多个电极同时受到刺激时ITD敏感度如何受到影响非常重要，因为复杂声音的表征需要多电极刺激。多电极刺激可能会因ITD敏感度较差的位置产生干扰，或因电流扩散导致通道相互作用，从而导致整体性能变差。另一方面，如果听众能够提取最可靠的可用ITD线索，多电极刺激可能会带来良好的整体敏感度。针对不同的多电极配置测量了ITD的刚可察觉差异（JND）。结果显示，多电极ITD的JND比最佳单电极对的ITD的JND要差。然而，与将刺激限制在阵列末端相比，沿整个阵列呈现ITD信息似乎能产生更好的敏感度，在阵列末端ITD的JND与最差单电极对相当。这些发现表明，仅在一个耳蜗区域呈现ITD可能并非在多电极刺激中最大化ITD敏感度的最佳方式。
