Abstract
Previous research has highlighted task-related differences in speech behaviour in normal speakers. Studies investigating speakers with dysarthria in this respect have observed performance patterns that deviate from the norm. A recurrent finding has been that these subjects were unable to alter their speech performance to the same degree as the control group. Various explanations have been put forward to account for this behaviour, which the current study has attempted to investigate further. The findings suggest that performance limitations are the basis for many of the observations. However, it was also noted that some subjects could not achieve the required changes despite otherwise normal levels of speech behaviour. The results suggest that the flexibility of the speech mechanism can be affected independently to maximum performance ability in speakers with dysarthria. The clinical implications of this finding are discussed.