ABSTRACT
BACKGROUND: The articulatory accuracy of patients with dysarthria is one of the most affected speech dimensions with a high impact on speech intelligibility. Behavioural treatments of articulation can either involve direct or indirect approaches. The latter have been thoroughly investigated and are generally appreciated for their almost immediate effects on articulation and intelligibility. The number of studies on (short-term) direct articulation therapy is limited. AIMS: To investigate the effects of short-term, boost articulation therapy (BArT) on speech intelligibility in patients with chronic or progressive dysarthria and the effect of severity of dysarthria on the outcome. METHODS & PROCEDURES: The study consists of a two-group pre-/post-test design to assess speech intelligibility at phoneme and sentence level and during spontaneous speech, automatic speech and reading a phonetically balanced text. A total of 17 subjects with mild to severe dysarthria participated in the study and were randomly assigned to either a patient-tailored, intensive articulatory drill programme or an intensive minimal pair training. Both training programmes were based on the principles of motor learning. Each training programme consisted of five sessions of 45 min completed within one week. OUTCOMES & RESULTS: Following treatment, a statistically significant increase of mean group intelligibility was shown at phoneme and sentence level, and in automatic sequences. This was supported by an acoustic analysis that revealed a reduction in formant centralization ratio. Within specific groups of severity, large and moderate positive effect sizes with Cohen's d were demonstrated. CONCLUSIONS & IMPLICATIONS: BArT successfully improves speech intelligibility in patients with chronic or progressive dysarthria at different levels of the impairment. What this paper adds What is already known on the subject Behavioural treatment of articulation in patients with dysarthria mainly involves indirect strategies, which have shown positive effects on speech intelligibility. However, there is limited evidence on the short-term effects of direct articulation therapy at the segmental level of speech. This study investigates the effectiveness of BArT on speech intelligibility in patients with chronic or progressive dysarthria at all severity levels. What this paper adds to existing knowledge The intensive and direct articulatory therapy programmes developed and applied in this study intend to reduce the impairment instead of compensating it. This approach results in a significant improvement of speech intelligibility at different dysarthria severity levels in a short period of time while contributing to exploit and develop all available residual motor skills in persons with dysarthria. What are the potential or actual clinical implications of this work? The improvements in intelligibility demonstrate the effectiveness of a BArT at the segmental level of speech. This makes it to be considered a suitable approach in the treatment of patients with chronic or progressive dysarthria.