Department of Otolaryngology - Head and Neck Surgery, University of California, Irvine, California 92697, USA.
J Acoust Soc Am. 2011 Jun;129(6):3934-45. doi: 10.1121/1.3570948.
Bilateral cochlear implant (BiCI) users gain an advantage in noisy situations from a second implant, but their bilateral performance falls short of normal hearing listeners. Channel interactions due to overlapping electrical fields between electrodes can impair speech perception, but its role in limiting binaural hearing performance has not been well characterized. To address the issue, binaural masking level differences (BMLD) for a 125 Hz tone in narrowband noise were measured using a pair of pitch-matched electrodes while simultaneously presenting the same masking noise to adjacent electrodes, representing a more realistic stimulation condition compared to prior studies that used only a single electrode pair. For five subjects, BMLDs averaged 8.9 ± 1.0 dB (mean ± s.e.) in single electrode pairs but dropped to 2.1 ± 0.4 dB when presenting noise on adjacent masking electrodes, demonstrating a negative impact of the additional maskers. Removing the masking noise from only the pitch-matched electrode pair not only lowered thresholds but also resulted in smaller BMLDs. The degree of channel interaction estimated from auditory nerve evoked potentials in three subjects was significantly and negatively correlated with BMLD. The data suggest that if the amount of channel interactions can be reduced, BiCI users may experience some performance improvements related to binaural hearing.
双侧人工耳蜗植入（BiCI）使用者从第二个植入体中获得了嘈杂环境下的优势，但他们的双侧表现仍不及正常听力的聆听者。由于电极之间重叠的电场引起的通道相互作用会损害语音感知，但它在限制双耳听力性能方面的作用尚未得到很好的描述。为了解决这个问题，使用一对音调匹配的电极测量了窄带噪声中 125 Hz 音调的双耳掩蔽级差（BMLD），同时将相同的掩蔽噪声呈现给相邻电极，与之前仅使用单个电极对的研究相比，这代表了一种更现实的刺激条件。对于五个受试者，在单个电极对中 BMLD 的平均值为 8.9 ± 1.0 dB（平均值 ± s.e.），但当在相邻掩蔽电极上呈现噪声时，BMLD 降至 2.1 ± 0.4 dB，表明额外掩蔽器的负面影响。仅从音调匹配电极对中去除掩蔽噪声不仅降低了阈值，而且还导致了更小的 BMLD。在三个受试者中，从听觉神经诱发电位估计的通道相互作用程度与 BMLD 呈显著负相关。数据表明，如果可以减少通道相互作用的程度，BiCI 用户可能会在与双耳听力相关的某些性能方面有所提高。
