Logo image
Back
Perceptual Outcome Measures for Supplementing Transcription Intelligibility in Speakers with Parkinson's Disease and Mild Dysarthria
Journal article   Peer reviewed

Perceptual Outcome Measures for Supplementing Transcription Intelligibility in Speakers with Parkinson's Disease and Mild Dysarthria

Jordan L. Manes, Kaila L. Stipancic, Lily Westemeyer, Andrea Rohl, Jeremy D. W. Greenlee, Nandakumar Narayanan, Ergun Uc and Kris Tjaden
Folia phoniatrica et logopaedica, 9422792
02/03/2026
DOI: 10.1159/000550174
PMCID: PMC12871864
PMID: 41632721

View Online

Abstract

Introduction: Intelligibility is the gold-standard metric of speech function in dysarthria; however, intelligibility alone may not capture subtle speech impairments. This study evaluated the extent to which related, but distinct, perceptual metrics of listener effort, speech severity, and speech naturalness were sensitive to mild speech impairment in speakers with Parkinson's disease (PD), providing supplemental information to transcription intelligibility. Methods: Speech samples were collected from 30 speakers with PD and 14 healthy controls. Listeners judged intelligibility using orthographic transcription and provided visual analog scale (VAS) judgments of listener effort, speech severity, and speech naturalness. A correlation analysis assessed the convergent validity between metrics. Linear mixed-effects analysis assessed differences between perceptual metrics. Results: VAS ratings of listener effort were most strongly correlated with intelligibility, while speech naturalness had the weakest relationship to other perceptual measures and the poorest listener reliability. Transcription intelligibility scores were equivalently high for PD and control groups. VAS ratings of listener effort, speech severity, and speech naturalness were significantly lower than intelligibility scores across both groups. Conclusion: For speakers with mild PD, transcription intelligibility did not capture subtle speech deficits detected by VAS metrics. Supplemental perceptual metrics provided a fuller picture of the speech impairment in these individuals. Mild changes in speech can occur in individuals with PD, but these changes are often difficult to detect using standard tests. The most common test, transcription intelligibility, measures how many words a listener can correctly understand and write down. However, this test often yields very high scores in cases of mild speech impairment, making it difficult to detect subtle differences in speech performance. This study examined whether three additional ways of rating speech - listener effort, speech severity, and speech naturalness - could help identify these subtle changes. Listener effort refers to how hard a listener must work to understand speech. Speech severity captures the overall degree of speech impairment, while speech naturalness reflects how typical the speech sounds. These ratings were collected using a sliding scale rather than fixed categories. All three measures provided a wider range of scores compared to transcription intelligibility, even though both PD and healthy older adults scored similarly on the intelligibility test. Listener effort was most strongly related to intelligibility, while naturalness appeared to capture a different aspect of speech and was rated less consistently by listeners. These findings suggest that listener effort and speech severity ratings may offer useful supplementary information when evaluating speech in individuals with PD, particularly when intelligibility scores are near perfect. Incorporating these additional perceptual measures may improve the ability to detect and monitor early or mild changes in speech associated with PD.
 Audiology & Speech-Language Pathology Life Sciences & Biomedicine Otorhinolaryngology Rehabilitation Science & Technology

Details

Metrics

1 Record Views
Logo image