Exploring the Temporal Variability of Speech Intensity, Speech Intelligibility, and Communicative Participation in Individuals with Hypophonia and Parkinson’s Disease
Abstract
Hypophonia, or reduced speech intensity, is frequently observed in individuals with Parkinson’s disease (PD). This speech deficit can impact speech intelligibility and communicative participation. However, there is little empirical evidence exploring the day-to-day variability of speech and communicative participation in individuals with PD. The purpose of this study is to investigate the temporal variability of acoustic and perceptual speech measures and psychosocial measures in individuals with hypophonia and PD. Additionally, this study seeks to examine the relationships among measures of speech intensity, speech intelligibility, self- and proxy-rated communicative participation, demographic factors, and non-speech factors. Twenty-three participants with PD, 23 primary communication partners, and 30 control participants attended three experimental visits. At each visit, participants completed questionnaires related to speech loudness and communicative participation. Participants with PD and control participants also performed speech intensity and speech intelligibility tasks. Variability in habitual speech intensity and Lombard response slope was found for participants with PD. Differences were found in maximum speech intensity, magnitude production, speech intelligibility, and self-perceived typical speech loudness for participants with PD and control participants. The results revealed similar self- and proxy-ratings of speech loudness in participants with PD. A significant difference was found between participants with PD and control participants across self-rated communicative participation measures. Greater variability was observed for the Communicative Participation Item Bank (CPIB), six questions of the Communicative Effectiveness Survey (CES), and two subsections of the Voice Activity and Participation Profile (VAPP) in participants with PD. Self- and proxy-rated communicative participation was comparable. Significant relationships were identified between maximum speech intensity and magnitude production, between speech intelligibility measures, between the CPIB and two VAPP subsections, between VAPP subsections, between proxy-ratings of typical speech loudness and six VAPP subsections, the CPIB and select CES questions, and VAPP subsections in participants with PD. A retest analysis involving reliability and repeatability estimates for all dependent measures was also reported. These findings contribute to the understanding of hypophonia in PD and may provide context in the interpretation of treatment outcomes in this clinical population.