Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Research School of Behavioural and Cognitive Neurosciences, Graduate School of Medical Sciences, University of Groningen, Groningen, The Netherlands.
Ear Hear. 2023;44(4):900-916. doi: 10.1097/AUD.0000000000001335. Epub 2023 Jan 25.
Understanding speech in real life can be challenging and effortful, such as in multiple-talker listening conditions. Fundamental frequency ( fo ) and vocal-tract length ( vtl ) voice cues can help listeners segregate between talkers, enhancing speech perception in adverse listening conditions. Previous research showed lower sensitivity to fo and vtl voice cues when speech signal was degraded, such as in cochlear implant hearing and vocoder-listening compared to normal hearing, likely contributing to difficulties in understanding speech in adverse listening. Nevertheless, when multiple talkers are present, familiarity with a talker's voice, via training or exposure, could provide a speech intelligibility benefit. In this study, the objective was to assess how an implicit short-term voice training could affect perceptual discrimination of voice cues ( fo+vtl ), measured in sensitivity and listening effort, with or without vocoder degradations.
Voice training was provided via listening to a recording of a book segment for approximately 30 min, and answering text-related questions, to ensure engagement. Just-noticeable differences (JNDs) for fo+vtl were measured with an odd-one-out task implemented as a 3-alternative forced-choice adaptive paradigm, while simultaneously collecting pupil data. The reference voice either belonged to the trained voice or an untrained voice. Effects of voice training (trained and untrained voice), vocoding (non-vocoded and vocoded), and item variability (fixed or variable consonant-vowel triplets presented across three items) on voice cue sensitivity ( fo+vtl JNDs) and listening effort (pupillometry measurements) were analyzed.
Results showed that voice training did not have a significant effect on voice cue discrimination. As expected, fo+vtl JNDs were significantly larger for vocoded conditions than for non-vocoded conditions and with variable item presentations than fixed item presentations. Generalized additive mixed models analysis of pupil dilation over the time course of stimulus presentation showed that pupil dilation was significantly larger during fo+vtl discrimination while listening to untrained voices compared to trained voices, but only for vocoder-degraded speech. Peak pupil dilation was significantly larger for vocoded conditions compared to non-vocoded conditions and variable items increased the pupil baseline relative to fixed items, which could suggest a higher anticipated task difficulty.
In this study, even though short voice training did not lead to improved sensitivity to small fo+vtl voice cue differences at the discrimination threshold level, voice training still resulted in reduced listening effort for discrimination among vocoded voice cues.
在多说话人聆听环境中，理解真实生活中的言语可能具有挑战性且需要付出努力。基频（fo）和声道长度（vtl）的嗓音线索可以帮助听者区分说话人，从而提高不利聆听条件下的言语感知能力。先前的研究表明，与正常听力相比，在耳蜗植入听力和声码器聆听等语音信号受损的情况下，对 fo 和 vtl 嗓音线索的敏感性降低，这可能导致在不利聆听条件下理解言语的困难。然而，当存在多个说话人时，通过培训或暴露对说话人声音的熟悉程度可能会提供言语可懂度方面的益处。在这项研究中，我们的目的是评估在存在声码器失真的情况下，通过聆听大约 30 分钟的书籍片段录音并回答与文本相关的问题（以确保参与度）进行的短期语音内隐培训如何影响嗓音线索（fo+vtl）的感知辨别能力，以敏感度和聆听努力度作为衡量标准。
通过聆听书籍片段录音并回答与文本相关的问题（以确保参与度）进行语音培训，培训时长约 30 分钟。嗓音线索辨别力的差异（fo+vtl 的 just-noticeable differences，JNDs）通过作为三择一自适应范式的异类辨别任务进行测量，同时收集瞳孔数据。参考语音来自接受过培训的语音或未经培训的语音。分析语音培训（接受过培训的语音和未经培训的语音）、声码化（未声码化和已声码化）和项目变异性（在三个项目中呈现固定或可变的辅音-元音三元组）对嗓音线索敏感性（fo+vtl JNDs）和聆听努力度（瞳孔测量）的影响。
结果表明，语音培训对嗓音线索辨别力没有显著影响。正如预期的那样，与非声码化条件相比，声码化条件下的 fo+vtl JNDs 显著增大，与固定项目呈现相比，变量项目呈现时的 fo+vtl JNDs 也显著增大。在刺激呈现过程中瞳孔扩张的广义加性混合模型分析表明，与接受过培训的语音相比，在聆听未经培训的语音时，fo+vtl 辨别过程中的瞳孔扩张显著增大，但仅在声码化语音中如此。与非声码化条件相比，声码化条件下的瞳孔峰值扩张显著增大，与固定项目相比，变量项目增加了瞳孔基线，这可能表明任务难度预期更高。
在这项研究中，尽管短期语音培训并没有导致在辨别阈值水平上对 fo+vtl 小嗓音线索差异的敏感性提高，但语音培训仍可降低对声码化嗓音线索的辨别努力度。
