Singing and Speaking Ability in Parkinson's Disease and Spinocerebellar Ataxia

Purpose: This study examined spontaneous, spoken-to-a-model, and two sung modes in speakers with Parkinson's disease (PD), speakers with cerebellar dis-ease (CD), and healthy controls. Vocal performance was measured by intellig-ibility scores and listeners' perceptual ratings. Method: Participants included speakers with hypokinetic dysarthria secondary to PD, those with ataxic dysarthria secondary to CD, and healthy speakers. Partici-pants produced utterances in four vocal modes: spontaneous speech, spoken -to-a-model, sung-to-a-model, and spontaneous singing. For spoken-to-a-model and sung-to-a-model modes, written material was provided the model. For spon-taneous singing, participants sang songs that they endorsed as familiar. Depen-dent variables: In Experiment I, listeners orthographically transcribed the audio samples of the first three vocal modes. In Experiment IIa, raters evaluated the accuracy of the pitch and rhythm of the spontaneous singing of familiar songs. Finally, familiar songs and sung-to-a-model utterances were rated on a compe-tency scale by a second group of raters (Experiment IIb). Results: Results showed increases in intelligibility during the spoken-to-a -model mode compared with the spontaneous mode in both PD and CD groups. Singing enhanced the vocal output of speakers with PD more than in speakers with CD, as measured by percent intelligibility. PD participants' pitch and rhythm accuracy and competency in singing familiar songs was rated more favorably than those produced by CD participants. Conclusions: The findings reveal a vocal task effect for spoken utterances in both groups. Sung exemplars, more impaired in CD, suggest a significant involvement of the cerebellum in singing. Supplemental Material: https://doi.org/10.23641/asha.21809544

Automated summary

This study examined vocal performance in speakers with Parkinson's disease (PD), speakers with cerebellar disease (CD), and healthy controls in spontaneous, spoken-to-a-model, and sung modes. The results showed that intelligibility increased during the spoken-to-a-model mode compared with the spontaneous mode in both PD and CD groups. Singing enhanced the vocal output of speakers with PD more than in speakers with CD, as measured by percent intelligibility.