The Articulation Index and Speech Intelligibility Index predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the frequency-importance function, a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. The purpose of this study was to determine whether such importance functions could similarly characterize contributions of electrode channels in cochlear implant systems. Thirty-eight subjects with normal hearing listened to vowel-consonant-vowel tokens, either as recorded or as output from vocoders that simulated aspects of cochlear implant processing. Importance functions were measured using the method of Whitmal and DeRoy [J. Acoust. Soc. Am. >130, 4032–4043 (2011)], in which signal bandwidths were varied adaptively to produce specified token recognition scores in accordance with the transformed up-down rules of Levitt [J. Acoust. Soc. Am. >49, 467–477 (1971)]. Psychometric functions constructed from recognition scores were subsequently converted into importance functions. Comparisons of the resulting importance functions indicate that vocoder processing causes peak importance regions to shift downward in frequency. This shift is attributed to changes in strategy and capability for detecting voicing in speech, and is consistent with previously measured data.
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机译：清晰度指数和语音清晰度指数通过语音和听力参数的测量来预测清晰度分数。预测中的一个组成部分是频率重要性函数，它是一种加权函数，用于表征语音特定频谱区域对语音清晰度的贡献。这项研究的目的是确定这种重要性函数是否可以类似地表征耳蜗植入系统中电极通道的作用。 38名听力正常的受试者听了元音-辅音-元音标记，这些声音是记录的或模拟人工耳蜗植入过程的声码器的输出。重要性函数是使用Whitmal和DeRoy [J. co Soc。上午。 > 130 ，4032-4043（2011）]，其中，根据Levitt变换的上下规则，自适应地改变信号带宽以产生指定的令牌识别分数。 co Soc。上午。 > 49 ，第467-477页（1971年）]。随后将根据识别分数构建的心理测验功能转换为重要性功能。所得重要性函数的比较表明，声码器处理导致峰值重要性区域的频率向下移动。该变化归因于检测语音中发声的策略和能力的变化，并且与先前测量的数据一致。
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