Speech movement variability in people who stutter (Wiltshire et al., 2021)

<b>Purpose: </b>People who stutter (PWS) have more unstable speech motor systems than people who are typically fluent (PWTF). Here, we used real-time magnetic resonance imaging (MRI) of the vocal tract to assess variability and duration of movements of different articulators in PWS and PWTF during fluent speech production.<b>Method: </b>The vocal tracts of 28 adults with moderate to severe stuttering and 20 PWTF were scanned using MRI while repeating simple and complex pseudowords. Midsagittal images of the vocal tract from lips to larynx were reconstructed at 33.3 frames per second. For each participant, we measured the variability and duration of movements across multiple repetitions of the pseudowords in three selected articulators: the lips, tongue body, and velum.<b>Results: </b>PWS showed significantly greater speech movement variability than PWTF during fluent repetitions of pseudowords. The group difference was most evident for measurements of lip aperture using these stimuli, as reported previously, but here, we report that movements of the tongue body and velum were also affected during the same utterances. Variability was not affected by phonological complexity. Speech movement variability was unrelated to stuttering severity within the PWS group. PWS also showed longer speech movement durations relative to PWTF for fluent repetitions of multisyllabic pseudowords, and this group difference was even more evident as complexity increased.<b>Conclusions: </b>Using real-time MRI of the vocal tract, we found that PWS produced more variable movements than PWTF even during fluent productions of simple pseudowords. PWS also took longer to produce multisyllabic words relative to PWTF, particularly when words were more complex. This indicates general, trait-level differences in the control of the articulators between PWS and PWTF.<br><b>Supplemental Material S1.</b> Effect of word length on variability. <br><b>Supplemental Material S2. </b>Effect of phonological complexity on variability. <br><b>Supplemental Material S3. </b>Effect of word length on duration.<br><b>Supplemental Material S4. </b>Effect of phonological complexity on duration.<br>Wiltshire, C. E. E., Chiew, M., Chesters, J., Healy, M. P., &amp; Watkins, K. E. (2021). Speech movement variability in people who stutter: A vocal tract magnetic resonance imaging study. <i>Journal of Speech, Language, and Hearing Research</i>. Advance online publication. https://doi.org/10.1044/2021_JSLHR-20-00507

<b>目的：</b>口吃者（PWS）的言语运动系统比典型流利说话者（PWTF）更不稳定。本研究采用声道实时磁共振成像（MRI）技术，评估PWS与PWTF在流利言语产生过程中不同发音器官运动的变异性及持续时间。<b>方法：</b>对28名中重度口吃成人及20名PWTF的声道进行MRI扫描，期间受试者重复简单及复杂假词。声道从中唇到喉的矢状位中部图像以每秒33.3帧的速度重建。针对每位受试者，我们测量了其在假词多次重复过程中三个选定发音器官（嘴唇、舌体及软腭）运动的变异性与持续时间。<b>结果：</b>在流利重复假词时，PWS的言语运动变异性显著高于PWTF。正如先前研究报道，使用该刺激材料测量唇开度时组间差异最为明显，但本研究发现同一话语中舌体及软腭的运动亦受影响。变异性不受语音复杂性影响。PWS组内言语运动变异性与口吃严重程度无关。对于多音节假词的流利重复，PWS的言语运动持续时间亦长于PWTF，且随着复杂性增加，该组间差异更为显著。<b>结论：</b>通过声道实时MRI技术，我们发现即使在简单假词的流利产生过程中，PWS的运动变异性仍高于PWTF。PWS产生多音节词的时间亦长于PWTF，尤其是当词的复杂性增加时。这表明PWS与PWTF在发音器官控制方面存在普遍性、特质层面的差异。<br><b>补充材料S1：</b>词长对变异性的影响<br><b>补充材料S2：</b>语音复杂性对变异性的影响<br><b>补充材料S3：</b>词长对持续时间的影响<br><b>补充材料S4：</b>语音复杂性对持续时间的影响<br>Wiltshire, C. E. E., Chiew, M., Chesters, J., Healy, M. P., & Watkins, K. E. (2021). 口吃者的言语运动变异性：一项声道磁共振成像研究。《言语、语言与听力研究杂志》。在线优先出版。https://doi.org/10.1044/2021_JSLHR-20-00507