Characteristics of Speech Rates and Utterance Lengths in Fluent and Disfluent Utterances of Adults Who Stutter

Abstract

Purpose This study aimed to investigate differences of overall speaking rate, articulation rate, and utterance length (measured in mean length of utterance-morpheme, MLU-m) in three types of utterance in adults who stutter (AWS). Methods Participants (n = 50) performed reading and picture description tasks, and each utterance was categorized as a “fluent utterance” (not including any disfluencies), an “abnormal disfluencies (AD) utterance” (containing AD), or a “normal disfluencies (ND) utterance” (containing ND only). For each utterance type, mean overall speaking rate, mean articulation rate, and mean MLU-m were measured; these variables were used to compare utterance types in each task. Each participant’s AD rate and ND rate from Paradise Fluency Assessment-II were also measured for correlation analyses. Results In reading, overall speaking rate was faster in ND utterance than AD utterance, but in picture description, it was faster in fluent utterance compared to either other category. Regardless of tasks, articulation rate did not differ between utterance types. In both tasks, MLU-m was significantly the shortest in the fluent utterance. During reading, ND rate was negatively correlated with MLUm in the ND utterance. Conclusion Greater utterance length might trigger normal (linguistic) and abnormal disfluencies in AWS. Both utterance type and task influence overall speaking rate, suggesting these features be considered when assessing speech fluency in AWS. Key Words: Stuttering, Type of utterance, Overall speaking rate, Articulation rate, Mean length of utterance-morpheme 중심 단어: 말더듬, 발화 ìœ í˜•, ì „ì²´ë§ì†ë„, 조음속도, í‰ê· í˜•íƒœì†Œê¸¸ì´