Speech Hearing and Phonetic Sciences, University College London, UK.
Int J Audiol. 2012 May;51(5):389-98. doi: 10.3109/14992027.2011.642010. Epub 2011 Dec 27.
To assess the reliability of across-ear, acoustic-electric pitch/timbre comparisons for determining effective characteristic frequencies of cochlear implant electrodes.
Nine CI users with contralateral residual acoustic hearing.
Absolute acoustic thresholds in the unimplanted ear were measured and frequency selectivity was assessed via psychophysical tuning curves. An adjustment method was used to match the percepts elicited by pulse trains on individual electrodes with various acoustic signals (pure tones, narrow-band noises, and bandpass filtered pulse trains). The starting frequency of the acoustic signal was roved and matches were obtained at different loudness levels.
Acoustic frequency selectivity varied widely. Two subjects showed clear evidence of frequency selectivity extending above 500 Hz. Only these subjects produced consistent pitch matches over repeated measurements. For other subjects, the acoustic frequency eventually selected tended to correlate with the initially presented frequency. There was limited evidence of level effects and these were inconsistent across subjects and electrodes.
Across-modality pitch/timbre matching appears unlikely to provide a generally applicable method for determining the effective characteristic frequencies of cochlear implant electrodes. Frequency selectivity above 500 Hz may be necessary for consistent pitch/timbre matches.
评估跨耳声电音高/音色比较在确定人工耳蜗电极有效特征频率方面的可靠性。
9 名对侧残余听力的人工耳蜗使用者。
测量未植入耳的绝对听阈，并通过心理物理调谐曲线评估频率选择性。使用一种调整方法将个体电极上的脉冲串引起的知觉与各种声学信号（纯音、窄带噪声和带通滤波脉冲串）匹配。声学信号的起始频率在不同的响度水平上进行扫描，并获得匹配。
声频率选择性差异很大。两名受试者表现出明显的频率选择性延伸至 500Hz 以上的证据。只有这些受试者在重复测量中产生了一致的音高匹配。对于其他受试者，最终选择的声学频率往往与最初呈现的频率相关。有有限的证据表明存在水平效应，但这些效应在受试者和电极之间不一致。
跨模态音高/音色匹配似乎不太可能为确定人工耳蜗电极的有效特征频率提供一种普遍适用的方法。500Hz 以上的频率选择性可能是产生一致音高/音色匹配的必要条件。
