Chao Sara-Ching, Ochoa Damaris, Daliri Ayoub
Speech and Hearing Science, College of Health Solutions, Arizona State University, Tempe, AZ, United States.
Front Hum Neurosci. 2019 Mar 22;13:96. doi: 10.3389/fnhum.2019.00096. eCollection 2019.
Theoretical models of speech production suggest that the speech motor system (SMS) uses auditory goals to determine errors in its auditory output during vowel production. This type of error calculation indicates that within-speaker production variability of a given vowel is related to the size of the vowel's auditory goal. However, emerging evidence suggests that the SMS may also take into account perceptual knowledge of vowel categories (in addition to auditory goals) to estimate errors in auditory feedback. In this study, we examined how this mechanism influences within-speaker variability in vowel production. We conducted a study ( = 40 adults), consisting of a vowel categorization task and a vowel production task. The vowel categorization task was designed-based on participant-specific vowels-to estimate the categorical perceptual boundary (CPB) between two front vowels (/ε/ and /æ/). Using the vowel production data of each participant, we calculated a variability-based boundary (VBB) located at the "center of mass" of the two vowels. The inverse of the standard deviation of a vowel distribution was used as the "mass" of the vowel. We found that: (a) categorical boundary was located farther from more variable vowels; and (b) the calculated VBB (i.e., the center of mass of the vowels) significantly and positively correlated with the estimated categorical boundary ( = 0.912 for formants calculated in hertz; = 0.854 for formants calculated in bark). Overall, our findings support a view that vowel production and vowel perception are strongly and bidirectionally linked.
言语产生的理论模型表明，言语运动系统（SMS）在元音产生过程中利用听觉目标来确定其听觉输出中的误差。这种误差计算表明，给定元音在说话者内部的产生变异性与该元音听觉目标的大小有关。然而，新出现的证据表明，言语运动系统可能还会考虑元音类别的感知知识（除听觉目标外），以估计听觉反馈中的误差。在本研究中，我们考察了这种机制如何影响说话者内部元音产生的变异性。我们进行了一项研究（n = 40名成年人），包括一个元音分类任务和一个元音产生任务。元音分类任务是基于参与者特定的元音设计的，以估计两个前元音（/ε/和/æ/）之间的类别感知边界（CPB）。利用每个参与者的元音产生数据，我们计算了位于两个元音“质心”处的基于变异性的边界（VBB）。元音分布标准差的倒数被用作元音的“质量”。我们发现：（a）类别边界离变异性更大的元音更远；（b）计算出的VBB（即元音的质心）与估计的类别边界显著正相关（以赫兹计算的共振峰，r = 0.912；以巴克计算的共振峰，r = 0.854）。总体而言，我们的研究结果支持这样一种观点，即元音产生和元音感知紧密且双向地联系在一起。
