Stohl Joshua S, Throckmorton Chandra S, Collins Leslie M
Department of Electrical and Computer Engineering, Duke University, P.O. Box 90291, Durham, North Carolina 27708-0291, USA.
J Acoust Soc Am. 2008 Feb;123(2):1043-53. doi: 10.1121/1.2821980.
Cochlear implant subjects continue to experience difficulty understanding speech in noise and performing pitch-based musical tasks. Acoustic model studies have suggested that transmitting additional fine structure via multiple stimulation rates is a potential mechanism for addressing these issues [Nie et al., IEEE Trans. Biomed. Eng. 52, 64-73 (2005); Throckmorton et al., Hear. Res. 218, 30-42 (2006)]; however, results from preliminary cochlear implant studies have been less compelling. Multirate speech processing algorithms previously assumed a place-dependent pitch structure in that a basal electrode would always elicit a higher pitch percept than an apical electrode, independent of stimulation rate. Some subjective evidence contradicts this assumption [H. J. McDermott and C. M. McKay, J. Acoust. Soc. Am. 101, 1622-1630 (1997); R. V. Shannon, Hear. Res. 11, 157-189 (1983)]. The purpose of this study is to test the hypothesis that the introduction of multiple rates may invalidate the tonotopic pitch structure resulting from place-pitch alone. The SPEAR3 developmental speech processor was used to collect psychophysical data from five cochlear implant users to assess the tonotopic structure for stimuli presented at two rates on all active electrodes. Pitch ranking data indicated many cases where pitch percepts overlapped across electrodes and rates. Thus, the results from this study suggest that pitch-based tuning across rate and electrode may be necessary to optimize performance of a multirate sound processing strategy in cochlear implant subjects.
人工耳蜗植入者在理解噪声中的语音以及执行基于音高的音乐任务方面仍然存在困难。声学模型研究表明，通过多种刺激速率传输额外的精细结构是解决这些问题的一种潜在机制[Nie等人，《IEEE生物医学工程学报》52，64 - 73（2005年）；Throckmorton等人，《听觉研究》218，30 - 42（2006年）]；然而，初步的人工耳蜗研究结果并不那么令人信服。多速率语音处理算法以前假设存在位置依赖的音高结构，即基底电极总是比顶端电极引发更高的音高感知，而与刺激速率无关。一些主观证据与这一假设相矛盾[H. J. McDermott和C. M. McKay，《美国声学学会杂志》101，1622 - 1630（1997年）；R. V. Shannon，《听觉研究》11，157 - 189（1983年）]。本研究的目的是检验这样一个假设，即引入多种速率可能会使仅由位置 - 音高产生的音调拓扑音高结构无效。使用SPEAR3开发型语音处理器从五名人工耳蜗植入使用者那里收集心理物理学数据，以评估所有激活电极上以两种速率呈现的刺激的音调拓扑结构。音高排序数据表明，在许多情况下，电极和速率之间的音高感知存在重叠。因此，本研究结果表明，跨速率和电极的基于音高的调谐对于优化人工耳蜗植入者的多速率声音处理策略的性能可能是必要的。
