Temporal variability in sung productions of adolescents who stutter

Abstract

Singing has long been used as a technique to enhance and reeducate temporal aspects of articulation in speech disorders. In the present study, differences in temporal structure of sung versus spoken speech were investigated in stuttering. In particular, the question was examined if singing helps to reduce VOT variability of voiceless plosives, which would indicate enhanced temporal coordination of oral and laryngeal processes. Eight German adolescents who stutter and eight typically fluent peers repeatedly spoke and sang a simple German congratulation formula in which a disyllabic target word (e.g., /’ki:ta/) was repeated five times. Every trial, the first syllable of the word was varied starting equally often with one of the three voiceless German stops /p/, /t/, /k/. Acoustic analyses showed that mean VOT and stop gap duration reduced during singing compared to speaking while mean vowel and utterance duration was prolonged in singing in both groups. Importantly, adolescents who stutter significantly reduced VOT variability (measured as the Coefficient of Variation) during sung productions compared to speaking in word-initial stressed positions while the control group showed a slight increase in VOT variability. However, in unstressed syllables, VOT variability increased in both adolescents who do and do not stutter from speech to song. In addition, vowel and utterance durational variability decreased in both groups, yet, adolescents who stutter were still more variable in utterance duration independent of the form of vocalization. These findings shed new light on how singing alters temporal structure and in particular, the coordination of laryngeal-oral timing in stuttering. Future perspectives for investigating how rhythmic aspects could aid the management of fluent speech in stuttering are discussed. Learning outcomesReaders will be able to describe (1) current perspectives on singing and its effects on articulation and fluency in stuttering and (2) acoustic parameters such as VOT variability which indicate the efficiency of control and coordination of laryngeal-oral movements. They will understand and be able to discuss (3) how singing reduces temporal variability in the productions of adolescents who do and do not stutter and 4) how this is linked to altered articulatory patterns in singing as well as to its rhythmic structure.