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Speech fluency in apraxia of speech (Harmon et al., 2019)

posted on 15.07.2019 by Tyson G. Harmon, Adam Jacks, Katarina L. Haley
Purpose: Slowed speech and interruptions to the flow of connected speech are common in aphasia. These features are also observed during dual-task performance for neurotypical adults. The purposes of this study were to determine (a) whether indices of fluency related to cognitive–linguistic versus motor processing would differ between speakers with aphasia plus apraxia of speech (AOS) and speakers with aphasia only and (b) whether cognitive load reduces fluency in speakers with aphasia with and without AOS.
Method: Fourteen speakers with aphasia (7 with AOS) and 7 neurotypical controls retold short stories alone (single task) and while simultaneously distinguishing between a high and a low tone (dual task). Their narrative samples were analyzed for speech fluency according to sample duration, speech rate, pause/fill time, and repetitions per syllable.
Results: As expected, both speaker groups with aphasia spoke slower and with more pauses than the neurotypical controls. The speakers with AOS produced more repetitions and longer samples than controls, but they did not differ on these measures from the speakers with aphasia without AOS. Relative to the single-task condition, the dual-task condition increased the duration of pauses and fillers for all groups but reduced speaking rate only for the control group. Sample duration and frequency of repetitions did not change in response to cognitive load.
Conclusions: Speech output in aphasia becomes less fluent when speakers have to engage in simultaneous tasks, as is typical in everyday conversation. Although AOS may lead to more sound and syllable repetitions than normal, speaking tasks other than narrative discourse might better capture this specific type of disfluency. Future research is needed to confirm and expand these preliminary findings.

Supplemental Material S1. Discrimination between high- and low-frequency tones across three groups.

Supplemental Material S2. Two-way comparisons for speech fluency and tone discrimination variables.

Harmon, T. G., Jacks, A., & Haley, K. L. (2019). Speech fluency in acquired apraxia of speech during narrative discourse: Group comparisons and dual-task effects. American Journal of Speech-Language Pathology, 28, 905–914. https://doi.org/10.1044/2018_AJSLP-MSC18-18-0107

Publisher Note: This article is part of the Special Issue: Selected Papers From the 2018 Conference on Motor Speech—Clinical Science and Innovations.


This research was supported by a Dissertation Completion Fellowship Award provided by the University of North Carolina at Chapel Hill Graduate School.