How expertise and language familiarity influence perception of speech of people with Parkinson’s disease

ABSTRACT

Parkinson’s disease (PD) is a progressive neurological disorder characterized by several motor and non-motor manifestations. PD frequently leads to hypokinetic dysarthria, which affects speech production and often has a detrimental impact on everyday communication. Among the typical manifestations of hypokinetic dysarthria, speech and language therapists (SLTs) identify prosody as the most affected cluster of speech characteristics. However, less is known about how untrained listeners perceive PD speech and how affected prosody influences their assessments of speech. This study explores the perception of sentence type intonation and healthiness of PD speech by listeners with different levels of familiarity with speech disorders in Dutch. We investigated assessments and classification accuracy differences between Dutch-speaking SLTs (n = 18) and Dutch/non-Dutch speaking untrained listeners (n = 27 and n = 124, respectively). We collected speech data from 30 Dutch speakers diagnosed with PD and 30 Dutch healthy controls. The stimuli set consisted of short phrases from spontaneous and read speech and of phrases produced with different sentence type intonation. Listeners participated in an online experiment targeting classification of sentence type intonation and perceived healthiness of speech. Results indicate that both familiarity with speech disorders and with speakers’ language are significant and have different effects depending on the task type, as different listener groups demonstrate different classification accuracy. There is evidence that untrained Dutch listeners classify PD speech as unhealthy more accurately than both trained Dutch and untrained non-Dutch listeners, while trained Dutch listeners outperform the other two groups in sentence type classification.

KEYWORDS:

• Parkinson’s disease
• dysarthria
• speech perception
• prosody
• speech healthiness

Acknowledgments

We are very grateful to our colleagues from University Medical Center Groningen: Prof. Dr. Natasha Maurits, Dr. Bauke de Jong and Sanne Timmermans for their advice, collaboration and invaluable help with the data collection. We also thank Lea Busweiler, research assistant, for the help in the data collection. We are grateful to all the speakers and listeners who volunteered to participate in our study.

Data availability

The data that support the findings of this study are openly available in OSF at https://osf.io/mf4d5, DOI 10.17605/OSF.IO/MF4D5.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Notes

¹ dimension of imprecise consonants is sometimes considered as a component of prosodic insufficiency in hypokinetic dysarthria (Darley et al., 1969b; Duffy, 2012).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.