Implementing speech supplementation strategies: effects on intelligibility and speech rate of individuals with chronic severe dysarthria.

A growing body of experimental research suggests that speech supplementation strategies can markedly increase speech intelligibility for individuals with dysarthria (D. Beukelman & K. Yorkston, 1977; E. Crow & P. Enderby, 1989; L. Hunter, T. Pring, & S. Martin, 1991; K. C. Hustad & D. R. Beukelman, 2001). However, studies in which speech supplementation strategies were actually implemented by speakers with dysarthria are limited, leaving their clinical efficacy unknown. The present study compared intelligibility and speech rate differences following speaker implementation of 3 strategies (topic, alphabet, and combined topic and alphabet supplementation) and a habitual (noncued) speech control condition for 5 speakers with severe dysarthria. Results revealed that combined cues and alphabet cues yielded significantly higher intelligibility scores and slower speech rates than topic cues and noncued speech. Overall, topic cues and noncued speech did not differ from one another with regard to intelligibility or speech rate. Combined cues and alphabet cues did not differ from one another with regard to intelligibility; however, speech rate was significantly different between the 2 strategies. Individual differences among speakers were generally consistent with group findings. Results were somewhat different from previous research in which strategies were experimentally superimposed on the habitual speech signal. However, findings provide evidence that alphabet cues and combined cues can have an important effect on intelligibility for speakers with severe dysarthria.