Effects of delayed auditory feedback and structured motor learning approach in enhancing speech intelligibility in individuals with Parkinson's disease: A proof-of-concept study

Abstract

The proposed study assessed speech intelligibility gains and long-term retention, if any, through administering delayed auditory feedback (DAF) to people with hypokinetic dysarthria secondary to Parkinson's disease (HPSPD) within a structured motor learning approach. In this pre/post treatment design, eight participants practiced fifteen Harvard sentences five times each using DAF + structured motor learning approach for six consecutive days. Participant productions without DAF or feedback were recorded for purpose of perceptual data analysis before treatment began, immediately after six days of treatment, and one-month post-treatment. Fifteen naive listeners rated the participant's productions using perceptual outcome measures of speech intelligibility. The results of perceptual analysis revealed that participants' speech production was rated significantly more intelligible at immediate retention and delayed retention sessions in comparison to the baseline. The findings support our initial hypothesis that treatment incorporating DAF and structured motor learning would not only improve the participants' speech intelligibility but also facilitate long-term retention. The current findings also indicated that the participants continued to maintain their improved speech intelligibility after one month following the treatment. This is the first study to our knowledge that informs us of the outcomes of a novel treatment line that combined DAF accompanied with a structured motor learning approach. Further research must be conducted to generalize these findings; this line of research can have significant ramifications on service-delivery models in speech-language pathology for patients with HPSPD.