Perception of vocal emotions produced by Cantonese speakers with hypokinetic dysarthria

Abstract

Hypokinetic dysarthria is the most common type of speech disorder associated with Parkinson’s disease (PD). Individuals with hypokinetic dysarthria were found to have impaired prosody. The purpose of this study was to investigate the perception of vocal emotions conveyed by Cantonese speakers with hypokinetic dysarthria associated with PD, in comparison to healthy controls. Perceptual ratings of four perceptual dimensions (loudness level, pitch height, pitch variability, speech rate) by listeners for speech samples produced by speakers with PD who intended to convey different emotions were also examined. Speech samples with six different intended emotions (happy, sad, disgust, surprised, angry, neutral) were previously collected from twenty speakers with hypokinetic dysarthria and seven healthy controls. Twenty listeners then identified the perceived vocal emotions and rated the four perceptual dimensions. Results showed that there was significant difference in the identification accuracy of vocal emotions between speakers with PD and healthy controls. In particular, vocal emotion angry conveyed by speakers with PD was significantly difficult for listeners to recognize. Also, listeners perceived the speech samples produced by speakers with PD to be with softer voice, lower pitch height, and smaller pitch variability when compared to those produced by healthy controls. These findings provide empirical evidence for the argument that vocal emotional communication is impaired in Cantonese speakers with hypokinetic dysarthria associated with PD. They also address the focus in treatment for improving expression of vocal emotions for individuals with PD.