Effect of speech rate manipulations on articulatory dynamics in severe traumatic brain injury: an EMA and EPG study.

Background: Manipulation of speech rate forms an integral part of the treatment of dysarthria and the effects of changes in speech rate on articulatory dynamics in persons with traumatic brain injury (TBI) is poorly documented.

Objective: To determine the effects of manipulations of speech rate (habitual vs fast) on lingual kinematics and tongue-to-palate contacts in adult speakers with severe TBI and matched normal controls.

Materials And Methods: Six adults with severe TBI and five matched non-neurologically impaired controls underwent testing of their articulatory function using electromagnetic articulography (EMA) and electropalatography (EPG).

Results: The results demonstrated that the TBI and control groups selected different strategies for increasing speech rate, with the TBI group showing an increase in articulatory effort estimated from an increase in maximum velocity and maximum acceleration/deceleration of tongue movement when speaking at the fast rate. The control group demonstrated no effects of a fast speech rate on articulatory kinematics for sentence productions.

Conclusions: When speaking at a fast rate, individuals with severe TBI appear to use greater articulatory effort, possibly to preserve the distinctiveness of phonetic segments in order to avoid articulatory undershoot. In contrast, control subjects show a greater economy of effort when speaking at a fast rate, possibly to preserve articulatory precision.