Teoh Su Wooi, Neuburger Heidi S, Svirsky Mario A
DeVault Otologic Research Laboratory, Department of Otolaryngology, Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Ind. 46202, USA.
Audiol Neurootol. 2003 Sep-Oct;8(5):269-85. doi: 10.1159/000072000.
It is hypothesized that for postlingually deafened adult cochlear implant (CI) users, a significant source of their perceptual performance variability is attributable to differences in their ability to discriminate the basic perceptual cues that are important in speech recognition. Previous research on 'electric hearing' has identified consistent perceptual cues for vowel recognition. However, the results on consonant perception by CI users are less clear. The primary purpose of this study is to present a quantitative method of evaluating potential 'electric cues' used by CI users in consonant identification. Since the actual input signals to the auditory periphery of CI users are electric in nature, we elected to measure the CI electric discharge patterns in addition to the original acoustic waveforms. The characteristics of the electric discharge patterns in response to intervocalic consonants were quantified and correlated with the dimensions of CI patients' perceptual spaces, which were computed from multidimensional scaling analyses of their consonant confusion matrices. The results agree with most, but not all, commonly accepted acoustic cues used by normal-hearing listeners. The correlation findings also suggest that CI users employ different sets of 'electric cues' in perceiving consonants that differ in their manner of articulation. Specifically, spectral and temporal cues associated with slowly changing formant structures and transitions, and features associated with frication and high-frequency noise, are all highly correlated with the perceptual dimensions of all CI users. However, rapidly changing formant transitions, such as those present in stop consonants, did not appear to play a significant role in consonant recognition by more poorly performing CI subjects. The perceptual results were consistent with our physical findings that the SPEAK coding strategy partially degraded the rapidly changing formant transitions.
据推测，对于语后聋成年人工耳蜗（CI）使用者而言，其感知性能差异的一个重要来源在于他们辨别语音识别中重要基本感知线索的能力存在差异。先前关于“电听觉”的研究已确定了元音识别中一致的感知线索。然而，CI使用者在辅音感知方面的结果尚不太明确。本研究的主要目的是提出一种定量方法，以评估CI使用者在辅音识别中使用的潜在“电线索”。由于CI使用者听觉外周的实际输入信号本质上是电信号，我们除了测量原始声学波形外，还选择测量CI的放电模式。对元音间辅音的放电模式特征进行量化，并与CI患者感知空间的维度相关联，该维度是通过对其辅音混淆矩阵的多维标度分析计算得出的。结果与正常听力听众使用的大多数（但并非全部）普遍接受的声学线索一致。相关性研究结果还表明，CI使用者在感知发音方式不同的辅音时采用了不同的“电线索”集合。具体而言，与缓慢变化的共振峰结构和过渡相关的频谱和时间线索，以及与摩擦和高频噪声相关的特征，都与所有CI使用者的感知维度高度相关。然而，快速变化的共振峰过渡，如塞音中出现的那些，在表现较差的CI受试者的辅音识别中似乎并未发挥重要作用。感知结果与我们的物理发现一致，即SPEAK编码策略部分地削弱了快速变化的共振峰过渡。
