Speech stability as a characteristic of the individual

Coarticulation, the influence of one speech sound on another in running speech, has been suggested as an index of speech motor control. Therefore, proficient and stable coarticulation could be a diagnostic tool in language assessment and speech-language pathology. In the present study, stability in the production of velar-vowel coarticulation was measured within speakers across experimental sessions to determine whether differences in stability can be attributed to individual differences in speech production ability. Velar-vowel coarticulation was recorded in children aged 8-12 in three sessions roughly one month apart. Participants recited sentences that included a target word starting with /k/ + vowel. Ultrasound images were analyzed to identify tongue posture and stability in posture across repetitions following procedures of Frisch, Maxfield, & Belmont (2016, Clinical Linguistics & Phonetics, doi:10.3109/02699206.2015.1137632). Preliminary analysis of two participants suggests there is less variation in stability within a participant across sessions than there is between participants. Analysis of the remaining participants is ongoing. This suggests that speech stability may indeed be a property of an individual speaker. If this finding holds, there are implications for models of speech production that include individual differences, including differences in language proficiency or clinical diagnosis.