Pfingst Bryan E, Burkholder-Juhasz Rose A, Xu Li, Thompson Catherine S
Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan 48109-5616, USA.
J Acoust Soc Am. 2008 Feb;123(2):1054-62. doi: 10.1121/1.2828051.
In modern cochlear implants, much of the information required for recognition of important sounds is conveyed by temporal modulation of the charge per phase in interleaved trains of electrical pulses. In this study, modulation detection thresholds (MDTs) were used to assess listeners' abilities to detect sinusoidal modulation of charge per phase at each available stimulation site in their 22-electrode implants. Fourteen subjects were tested. MDTs were found to be highly variable across stimulation sites in most listeners. The across-site patterns of MDTs differed considerably from subject to subject. The subject-specific patterns of across-site variability of MDTs suggest that peripheral site-specific characteristics, such as electrode placement and the number and condition of surviving neurons, play a primary role in determining modulation sensitivity. Across-site patterns of detection thresholds (T levels), maximum comfortable loudness levels (C levels) and dynamic ranges (DRs) were not consistently correlated with across-site patterns of MDTs within subjects, indicating that the mechanisms underlying across-site variation in these measures differed from those underlying across-site variation in MDTs. MDTs sampled from multiple sites in a listener's electrode array might be useful for diagnosing across-subject differences in speech recognition with cochlear implants and for guiding strategies to improve the individual's perception.
在现代人工耳蜗中，识别重要声音所需的大部分信息是通过交错排列的电脉冲序列中每个相位的电荷的时间调制来传递的。在本研究中，调制检测阈值（MDTs）被用于评估受试者在其22电极植入物的每个可用刺激部位检测每个相位电荷的正弦调制的能力。对14名受试者进行了测试。结果发现，在大多数受试者中，MDTs在不同刺激部位之间存在很大差异。MDTs的跨部位模式在不同受试者之间差异很大。MDTs跨部位变异性的受试者特异性模式表明，外周部位特异性特征，如电极放置以及存活神经元的数量和状况，在决定调制敏感性方面起主要作用。检测阈值（T水平）、最大舒适响度水平（C水平）和动态范围（DRs）的跨部位模式与受试者内MDTs的跨部位模式并不始终相关，这表明这些测量中跨部位变化的潜在机制与MDTs中跨部位变化的潜在机制不同。从受试者电极阵列中的多个部位采样的MDTs可能有助于诊断人工耳蜗使用者在语音识别方面的个体差异，并指导改善个体感知的策略。
