Variability in Apraxia of Speech: A Perceptual and VOT Analysis of Stop Consonants‪.‬

This investigation was designed to examine the effects of (1) method of stimuli presentation and (2) sampling over time on production of stop consonants with a speaker with acquired apraxia of speech. Stimuli were presented in a blocked format and a randomized format on three sampling occasions and percentage of perceived errors, types of errors, consistency of errors, and voice onset times (VOTs) were evaluated. Results indicated that errors were more predictable in the blocked condition, particularly for the voiced stops. Furthermore, the type of errors observed varied greatly across presentation conditions. Overall percentages of errors were more consistent between the first and second sampling occasions (separated by 1 day) than between the first and third occasions (separated by 1 week). VOT values varied significantly across sampling conditions, with more differences seen for voiced stops in the blocked condition. These results highlight the need to consider the manner in which speech samples are elicited as well as the potential differences in patterns of responding across sounds when evaluating variability in acquired apraxia of speech (AOS). **********