The Effects of Intensive Voice Treatment in Mandarin Speakers With Parkinson’s Disease: Acoustic and Perceptual Findings

Purpose: This study investigated the effects of intensive voice treatment on subjective and objective measures of speech production in Mandarin speakers with hypokinetic dysarthria. Method: Nine Mandarin speakers with hypokinetic dysarthria due to Parkinson’s disease received 4 weeks of intensive voice treatment (4 × 60 min per week). The speakers were recorded reading a passage before treatment (PRE), immediately after treatment (POST), and at 6-month follow-up (FU). Listeners (n = 15) rated relative ease of understanding (EOU) of paired speech samples on a visual analogue scale. Acoustic analyses were performed. Changes in EOU, vocal intensity, global and local fundamental frequency (f_o) variation, speech rate, and acoustic vowel space area (VSA) were examined. Results: Increases were found in EOU and vocal intensity from PRE to POST and from PRE to FU, with no change found from POST to FU. Speech rate increased from PRE to POST, with limited evidence of an increase from PRE to FU and no change from POST to FU. No changes in global or local f_o variation or in VSA were found. Conclusions: Intensive voice treatment shows promise for improving speech production in Mandarin speakers with hypokinetic dysarthria. Vocal intensity, speech rate, and, crucially, intelligibility, may improve for up to 6 months posttreatment. In contrast, f_o variation and VSA may not increase following the treatment. Supplemental Material: https://doi.org/10.23641/asha.19529017.