Music and tone perception with dichotic stimulations

描述（申请人提供）：在过去的二十年里，许多重度失聪的人从人工耳蜗中受益。人工耳蜗提供的语言感知已被证明是相当成功的。然而，用目前的人工耳蜗系统来感知声调语言中的音乐或词汇音调仍然是一个挑战。这是因为只有几个电极提供的电刺激的低光谱分辨率阻止了音高信息的传输。目前的研究项目是提出检查可能的好处，双侧植入提供增加光谱分辨率，从而改善音乐和音调感知。使用双侧植入物，可以用更多的频带来分析输入信号，频带的数量等于两个植入物中电极的总数。信道是二分类分布的，即奇数索引信道分配到一只耳朵，偶数索引信道分配到另一只耳朵。因此，两种植入物中的每个电极都能接收到单独的但两倍精确的光谱信息。与分配相同通道或重复光谱信息的传统双侧植入物相比，这种新策略使双侧植入物的光谱分辨率提高了一倍。提出的新策略将使用噪声激发声码器进行模拟，并在双侧植入患者中进行验证。该研究的具体目的是：(1)评估通过双重刺激使频谱分辨率加倍的新策略对音乐和音调感知有多大好处；(2)测试在两个植入物的相对位置被操纵的情况下，两种呈现的刺激融合得如何。对于音乐感知，将使用传统的熟悉旋律识别测试。此外，还将使用修改后的旋律测试，要求听者检测旋律中特定音符的音高变化。对于词汇语气感知，将使用四种备选强迫选择范式。语音测试（即辅音和元音识别测试）也将包括在这两个具体目标中。本研究的结果将进一步加深我们对声学和电听觉中复杂信号的频谱融合机制的认识。该策略的成功将大大改善双侧种植体的音乐和音调感知，从而大大提高双侧种植体使用者的生活质量。

DESCRIPTION (provided by applicant): Many profoundly deafened people have benefited from cochlear implant in the past twenty years. Speech perception provided by cochlear implants has proven to be quite successful. It is still a challenge, however, to perceive music or lexical tone in tone languages with the current cochlear implant system. That is because the low spectral resolution in the electric stimulation provided by only a few electrodes prevents pitch information from being transmitted. The present research project is proposed to examine the possible benefits that bilateral implantation provides for increasing spectral resolution, hence improving music and tone perception. With a bilateral implant, an input signal can be analyzed with more frequency bands, the number of which equals the total number of electrodes in both implants. The channels are to be dichotically distributed, that is, the odd-index channels are assigned to one ear, and the even-index channel assigned to the other. Each electrode in both implants therefore receives exclusive but twice as refined spectral information. This new strategy doubles spectral resolution in bilateral implants compared to traditional bilateral implants that are assigned with same channels or repeated spectral information. The proposed new strategy will be simulated using a noise-excited vocoder and validated in bilateral implant patients. The specific aims of the study are (1) to evaluate how much music and tone perception benefits from the new strategy that doubles spectral resolution via dichotic stimulation; and (2) to test how well the dichotically presented stimuli fuse under conditions in which the relative position of the two implants is manipulated. For music perception, a traditional familiar melody recognition test will be used. In addition, a modified melody test will be used, in which the listeners are required to detect pitch changes made to particular notes in a melody. For lexical tone perception, a four-alternative forced choice paradigm will be used. Speech tests (i.e., consonant and vowel recognition tests) will also be included in both specific aims. The results of the present study will further our knowledge regarding the mechanisms of spectral fusion of complex signals in both acoustic and electric hearing. The success of this strategy will greatly improve music and tone perception with bilateral implantation, hence considerably improving the life quality of bilateral implant users.