Usler Evan R, Walsh Bridget
Department of Speech, Language, and Hearing Sciences, Boston University, MA.
Speech and Feeding Disorders Laboratory, MGH Institute of Health Professions, Boston, MA.
J Speech Lang Hear Res. 2018 Sep 19;61(9):2157-2167. doi: 10.1044/2018_JSLHR-S-17-0435.
Early childhood stuttering is associated with atypical speech motor development. Compared with children who do not stutter (CWNS), the speech motor systems of school-age children who stutter (CWS) may also be particularly susceptible to breakdown under increased processing demands. The effects of increased syntactic complexity and sentence length on articulatory coordination were investigated.
Kinematic, temporal, and behavioral indices of articulatory coordination were quantified for school-age CWS (n = 19) and CWNS (n = 18). Participants produced 4 sentences varying in syntactic complexity (simple declarative/complex declarative with a relative clause) and sentence length (short/long). Lip aperture variability (LAVar) served as a kinematic measure of interarticulatory consistency over repeated productions. Articulation rate (syllables per second) was also calculated as a related temporal measure. Finally, we computed accuracy and stuttering frequency percentages for each sentence to assess task performance.
Increased sentence length, but not syntactic complexity, increased LAVar in both groups. This effect was disproportionately greater for CWS compared with CWNS. No group differences were observed for articulation rate. CWS were also less accurate in their sentence productions than fluent peers and exhibited more instances of stuttering when processing demands associated with length and syntactic complexity increases.
The speech motor systems of school-age CWS appear to be particularly vulnerable to processing demands associated with increased sentence length, as evidenced by increased LAVar. Increasing the length and complexity of the sentence stimuli also resulted in reduced production accuracy and increased stuttering frequency. We discuss these findings within a motor control framework of speech production.
幼儿口吃与非典型言语运动发育有关。与不口吃的儿童（CWNS）相比，口吃的学龄儿童（CWS）的言语运动系统在处理需求增加时可能也特别容易出现功能障碍。研究了句法复杂性和句子长度增加对发音协调性的影响。
对学龄期口吃儿童（n = 19）和不口吃儿童（n = 18）的发音协调性的运动学、时间和行为指标进行量化。参与者说出4个句子，这些句子在句法复杂性（简单陈述句/带有关系从句的复杂陈述句）和句子长度（短/长）上有所不同。唇部开口度变异性（LAVar）作为重复发音时关节间一致性的运动学指标。发音速率（每秒音节数）也作为相关的时间指标进行计算。最后，我们计算了每个句子的准确性和口吃频率百分比，以评估任务表现。
句子长度增加，但句法复杂性未增加，两组的LAVar均增加。与CWNS相比，CWS的这种影响更大。两组在发音速率上未观察到差异。与流利的同龄人相比，CWS在句子产出上也不太准确，并且在与长度和句法复杂性增加相关的处理需求下表现出更多的口吃情况。
学龄期口吃儿童的言语运动系统似乎特别容易受到与句子长度增加相关的处理需求的影响，LAVar增加证明了这一点。句子刺激长度和复杂性的增加也导致产出准确性降低和口吃频率增加。我们在言语产生的运动控制框架内讨论这些发现。
