Meng Qinglin, Zheng Nengheng, Li Xia
IEEE Trans Neural Syst Rehabil Eng. 2017 Jun;25(6):641-649. doi: 10.1109/TNSRE.2016.2593489. Epub 2016 Jul 20.
Lexical tone recognition with current cochlear implants (CI) remains unsatisfactory due to significantly degraded pitch-related acoustic cues, which dominate the tone recognition by normal-hearing (NH) listeners. Several secondary cues (e.g., amplitude contour, duration, and spectral envelope) that influence tone recognition in NH listeners and CI users have been studied. This work proposes a loudness contour manipulation algorithm, namely Loudness-Tone (L-Tone), to investigate the effects of loudness contour on Mandarin tone recognition and the effectiveness of using loudness cue to enhance tone recognition for CI users. With L-Tone, the intensity of sound samples is multiplied by gain values determined by instantaneous fundamental frequencies (F0s) and pre-defined gain- F0 mapping functions. Perceptual experiments were conducted with a four-channel noise-band vocoder simulation in NH listeners and with CI users. The results suggested that 1) loudness contour is a useful secondary cue for Mandarin tone recognition, especially when pitch cues are significantly degraded; 2) L-Tone can be used to improve Mandarin tone recognition in both simulated and actual CI-hearing without significant negative effect on vowel and consonant recognition. L-Tone is a promising algorithm for incorporation into real-time CI processing and off-line CI rehabilitation training software.
由于与音高相关的声学线索显著退化，当前人工耳蜗（CI）的词汇声调识别仍然不尽人意，而这些线索在正常听力（NH）听众的声调识别中占主导地位。已经对一些影响NH听众和CI使用者声调识别的次要线索（例如，幅度轮廓、时长和频谱包络）进行了研究。这项工作提出了一种响度轮廓操纵算法，即响度-声调（L-声调），以研究响度轮廓对汉语声调识别的影响，以及使用响度线索增强CI使用者声调识别的有效性。使用L-声调时，声音样本的强度乘以由瞬时基频（F0）和预定义的增益-F0映射函数确定的增益值。在NH听众和CI使用者中使用四通道噪声带声码器模拟进行了感知实验。结果表明：1）响度轮廓是汉语声调识别的一个有用的次要线索，尤其是在音高线索显著退化时；2）L-声调可用于改善模拟和实际CI听力中的汉语声调识别，而对元音和辅音识别没有显著负面影响。L-声调是一种很有前景的算法，可纳入实时CI处理和离线CI康复训练软件中。
