Luo Xin, Fu Qian-Jie
Communication and Auditory Neuroscience, House Ear Institute, 2100 West Third Street, Los Angeles, California 90057, USA.
J Acoust Soc Am. 2009 May;125(5):3223-33. doi: 10.1121/1.3106534.
Because of the poor spectral resolution in cochlear implants (CIs), fundamental frequency (F0) cues are not well preserved. Chinese-speaking CI users may have great difficulty understanding speech produced by competing talkers, due to conflicting tones. In this study, normal-hearing listeners' concurrent Chinese syllable recognition was measured with unprocessed speech and CI simulations. Concurrent syllables were constructed by summing two vowels from a male talker (with identical mean F0's) or one vowel from each of a male and a female talker (with a relatively large F0 separation). CI signal processing was simulated using four- and eight-channel noise-band vocoders; the degraded spectral resolution may limit listeners' ability to utilize talker and/or tone differences. The results showed that concurrent speech recognition was significantly poorer with the CI simulations than with unprocessed speech. There were significant interactions between the talker and speech-processing conditions, e.g., better tone and syllable recognitions with the male-female condition for unprocessed speech, and with the male-male condition for eight-channel speech. With the CI simulations, competing tones interfered with concurrent-tone and syllable recognitions, but not vowel recognition. Given limited pitch cues, subjects were unable to use F0 differences between talkers or tones for concurrent Chinese syllable recognition.
由于人工耳蜗（CI）的频谱分辨率较差，基频（F0）线索无法得到很好的保留。说中文的CI使用者可能会因声调冲突而在理解竞争说话者发出的语音时遇到很大困难。在本研究中，通过未处理语音和CI模拟来测量听力正常的听众对中文音节的同时识别。同时出现的音节是通过将男性说话者的两个元音（平均F0相同）相加，或男性和女性说话者各一个元音（F0有较大差异）构建而成。使用四通道和八通道噪声带声码器模拟CI信号处理；频谱分辨率的降低可能会限制听众利用说话者和/或声调差异的能力。结果表明，与未处理语音相比，CI模拟的同时语音识别明显较差。在说话者和语音处理条件之间存在显著的交互作用，例如，对于未处理语音，男女条件下的声调及音节识别更好；对于八通道语音，男男条件下的识别更好。在CI模拟中，竞争声调会干扰同时出现的声调及音节识别，但不会干扰元音识别。由于音高线索有限，受试者无法利用说话者或声调之间的F0差异进行同时中文音节识别。
