Investigating Speech Rate and Utterance Length Demands in Preschool Children Who Stutter: Insights from the Demands and Capacities Model

One interactional perspective on stuttering is proposed by the Demands-Capacities Model (D-C Model) (Starkweather, 1987). While numerous studies have examined various demands, such as speech rate, utterance length, and turn-taking time, relatively few have investigated the occurrence of stuttering in relation to the discrepancy between demands and capacities in individual cases. This study aims to examine the impact of (1) the child`s utterance length and (2) the discrepancy between the guardian and the child in speech rate and utterance length on the frequency of stuttering.Thirteen native Japanese-speaking children who stutter, aged between 30 and 75 months, and their guardians participated in this study. Three conversational samples during play were collected from each dyad in their respective homes. Among these, the sample with the highest frequency of guardian-child interactions was selected and transcribed into text. In the transcript, conversational turns were identified, and each utterance was segmented into bunsetsu, a linguistic unit in Japanese. Utterance length was defined as the number of bunsetsu in a sentence with a coherent meaning, while speech rate was calculated by dividing the duration of the sentence by the number of morae. Only fluent utterances, free of stuttering, were used to determine speech rate. Stuttering frequency was quantified as the percentage of bunsetsu containing stuttering-like disfluencies (SLD). From the perspective of the D-C Model, the correlation between the discrepancy in speech rate between each guardian and their child and the child`s SLD frequency was analyzed, but no significant correlation was found. In contrast, a significant correlation was observed between the discrepancy in utterance length between each guardian and their child and the child`s SLD frequency (r = -0.588, p < 0.05, Spearman`s rank correlation). Additionally, children`s utterances containing SLD were significantly longer than those without SLD (p = 0.001, t-test). Regarding utterance length, the findings suggest that both internal demands (the child`s own speech length) and external stimuli (the guardian`s speech length) influence the child`s speech fluency.This study underscores the need for `tailor-made` environmental adjustments to accommodate each child`s developmental stage.

References

Starkweather, C. W. (1987). Fluency and stuttering. Prentice-Hall.