Speech and Swallow Kinematics of a Person with Congenital Aglossia

Abstract

Objective: This research study explored movement of key processes during speech and swallow of a person with congenital aglossia. It expands upon earlier studies that found a high degree of intelligibility among listeners for expressive speech by the person with congenital aglossia and seeks to identify the dynamics through which the articulators accomplish this phenomenon. Methods: Positional movements of the mandible and hyoid bone and mylohyoid and tongue base for speech and swallow were compared with those movements obtained for people without aglossia. Results: In this subject, the hyoid bone and mandible were strongly associated with movement of the pseudo tongue for both speech and swallow. This is markedly different from results of normal subjects, who show strong correlations between the hyoid bone and mandible and the tongue for swallow only. Kinematics differed significantly for speech and swallow tasks in the person with PwCA, with the exception of the hyoid bone, which behaved in a similar manner for both tasks. Movements of pseudo-tongue structures demonstrated a variety of horizontal and vertical movements, with some independent relationships between mandibular and hyoid bone motions for both oral swallow and speech. Overall, the dependent variables of mylohyoid and the base of tongue were closely related to the movement of the hyoid bone, which was the strongest determinant of vertical dependent variable movement. Results revealed that in this person with congenital aglossia, the hyoid bone and mandible were strongly associated with movement of the pseudo tongue for both speech and swallow. This is markedly different from results of normal subjects, who show strong correlations between the hyoid bone and mandible and the tongue for swallow only. Conclusion: These results suggest that speakers who present with congenital or acquired structural and/or physiological reductions to the speech mechanism may present with the capacity to capitalize on a variety of actions during eating or swallowing to optimize the more finessed actions of speech. The highly predictable correlations of muscles for deglutition and speech suggest that this speaker essentially ‘bootstrapped’ muscular actions (and limitations therein) developed for deglutition and used them to buttress speech and resonance. These actions are quite different from those of individuals with a tongue, who recruit a variety of muscles for the diverse acts of speaking and swallowing.