Oral Articulatory Control in Childhood Apraxia of Speech

Abstract

Purpose: The purpose of this research was to examine spatial and temporal aspects of articulatory control in children with childhood apraxia of speech (CAS), children with speech delay characterized by an articulation/phonological impairment (SD), and controls with typical development (TD) during speech tasks that increased in word length.

Method: The participants included 33 children (11 CAS, 11 SD, and 11 TD) between 3 and 7 years of age. A motion capture system was used to track jaw, lower lip, and upper lip movement during a naming task. Movement duration, velocity, displacement, and variability were measured from accurate word productions.

Results: Movement variability was significantly higher in the children with CAS compared with participants in the SD and TD groups. Differences in temporal control were seen between both groups of children with speech impairment and the controls with TD during accurate word productions. As word length increased, movement duration and variability differed between the children with CAS and those with SD.

Conclusions: These findings provide evidence that movement variability distinguishes children with CAS from speakers with SD. Kinematic differences between the participants with CAS and those with SD suggest that these groups respond differently to linguistic challenges.

Figure 1.

Kinematic traces of jaw displacement, jaw velocity, and lip aperture corresponding to the utterance Pop. Point A indicates the onset of movement in the jaw displacement trajectory, and point B marks the movement offset.

Figure 2.

Normalized jaw movement trajectories and corresponding spatiotemporal indices (STI) associated with the utterance puppypop produced by one participant each in the childhood apraxia of speech (CAS), speech delay characterized by an articulation/phonological impairment (SD), and typical development (TD) groups.

Figure 3.

Mean total jaw movement duration and standard error associated with the production of Pop, puppet, and puppypop by participants in the childhood apraxia of speech (CAS), speech delay characterized by an articulation/phonological impairment (SD), and typical development (TD) groups. Number of participants included for the tokens Pop, puppet, and puppypop, respectively: CAS = 11, 10, and 8; SD = 11, 11, and 9; TD = 11, 11, and 10.

Figure 4.

(a) Mean average jaw displacement and standard error associated with the production of Pop, puppet, and puppypop by participants in the childhood apraxia of speech (CAS), speech delay characterized by an articulation/phonological impairment (SD), and typical development (TD) groups. Number of participants included for the tokens Pop, puppet, and puppypop, respectively: CAS = 11, 10, and 8; SD = 11, 11, and 9; TD = 11, 11, and 10. (b) Mean average lip aperture and standard error associated with the production of Pop, puppet, and puppypop by participants in the CAS, SD, and TD groups. Number of participants included for the tokens Pop, puppet, and puppypop, respectively: CAS = 8, 8, and 8; SD = 11, 11, and 9; TD = 11, 11, and 10.

Figure 5.

Mean jaw spatiotemporal index (STI) and standard error associated with the production of Pop, puppet, and puppypop by participants in the childhood apraxia of speech (CAS), speech delay characterized by an articulation/phonological impairment (SD), and typical development (TD) groups. Number of participants included for the tokens Pop, puppet, and puppypop, respectively: CAS = 11, 10, and 8; SD = 11, 11, and 9; TD = 11, 11, and 10.