Kinematic investigation of lingual movement in words of increasing length in acquired apraxia of speech

The current study aimed to use electromagnetic articulography (EMA) to investigate the effect of increasing word length on lingual kinematics in acquired apraxia of speech (AOS). Tongue-tip and tongue-back movement was recorded for five speakers with AOS and a concomitant aphasia (mean age=53.6 years; SD=12.60) during target consonant production (i.e. /t, s, k/ singletons; /kl, sk/clusters), for one and two syllable stimuli. The results obtained for each of the participants with AOS were individually compared to those obtained by a control group (n=12; mean age=52.08 years; SD=12.52). Results indicated that the participants with AOS exhibited longer movement durations and, in some instances, larger tongue movements during consonant singletons and consonant cluster constituents embedded within mono- and multisyllabic utterances. Despite this, two participants with AOS exhibited a word length effect that was comparable with the control speakers, and possibly indicative of an intact phonological system.