Dissertations and Theses @ UNI

Acoustic and Perceptual Measures of Stop Consonant Voicing in Parkinson’s Disease

Availability

Thesis (Electronic Copy Not Available)

Abstract

Neurodegenerative disease often leads to acoustic changes in speech sound production (Illner et al., 2023; Kim, 2017; Tjaden & Wilding, 2004). Voice onset time (VOT), the interval between the burst release of a stop consonant and the onset of vocal fold vibration, may differ between speakers with Parkinson’s disease (PD) and healthy controls (Forrest et al., 1989; Johansson et al., 2023; Lisker & Abramson, 1967; Whitfield et al., 2018). Limited research has investigated the relationship between VOT and perceived voicing in speakers with PD or assessed task differences in VOT in individuals with neurodegenerative disease. The present study compared VOT and VOT ratio (ratio of VOT to syllable duration) in initial oral stop consonants between speakers with PD and healthy controls (HC) during minimal pair productions and oral diadochokinesis (DDK). Listeners rated stop consonants in PD speakers’ minimal pair productions on a seven-point voiced voiceless continuum to determine how VOT and VOT ratio related to perceived voicing. Results indicated significant group differences in VOT for the voiceless stop consonants, /p, t/, in the minimal pairs task. The PD speakers demonstrated significantly reduced contrast between /b, p/ and /d, t/ for both VOT and VOT ratio relative to the HC group. Neither VOT nor VOT ratio differed significantly between groups in the DDK task. The mean perceived voicing ratings from minimal pair productions revealed high perceptual accuracy for all stop consonants, with VOT and VOT ratio significantly predicting perceived voicing. This study provides evidence that PD may result in acoustic speech changes that precede perceptible changes in speech sound production.

Year of Submission

2026

Degree Name

Master of Arts

Department

Department of Communication Sciences and Disorders

First Advisor

Sarah Diehl

Second Advisor

Todd Bohnenkamp

Third Advisor

Jaimie Gilbert

Date Original

2026

Object Description

1 PDF file (78 leaves)

Language

en

File Format

application/pdf

Electronic copy is not available through UNI ScholarWorks.

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