Objective: Presbyphonia is a voice disorder resulting from laryngeal changes due to ageing, manifested as degeneration of oral, laryngeal, and respiratory structures (Kost & Sataloff, 2020). Currently, the world is experiencing a growing elderly population (WHO, 2024). Up to 58% of individuals aged over 65 years exhibited varying vocal complaints (Davids et al., 2012). However, dysphonia among older adults has been somewhat overlooked, with limited evidence on the effectiveness of voice therapy for treating presbyphonia. While combined respiratory muscle strength training (cRMST) which integrates expiratory muscle strength training (EMST) and inspiratory muscle strength training (IMST) has shown efficacy in improving vocal function for other vocal issues such as Parkinson’s disease (Lewis, 2013), its impact on presbyphonia remains unexplored. This study aims to investigate the effects of cRMST on enhancing vocal function in individuals with presbyphonia.
Methods: The present study adopts a prospective, randomized controlled trial design, involving thirty-two participants who were randomly assigned to one of the following groups: (1) EMST; (2) IMST; (3) cRMST; (4) no intervention (control group). All participants were diagnosed with presbyphonia based on videostroboscopic examination and auditory perceptual voice evaluation. Participants in the experimental groups were instructed to complete a regimen of three sets of ten repetitions twice daily for seven days, with the load adjusted weekly based on the participant’s maximum expiratory pressure (MEP) or maximum inspiratory pressure (MIP). Vocal function was assessed before and after the four-week intervention using measures of pulmonary function (FVC), respiratory strength (MEP, MIP), aerodynamics (maximum phonation time), acoustics (percent jitter and shimmer, HNR, CPPs), auditory-perception (CAPE-V), and self-report (VHI-10).
Results: A two-way repeated-measure ANOVA was conducted to examine the main effects of time, groups, and their interaction effect. Post hoc group comparisons were performed using Tukey's test. The preliminary data revealed a significant improvement in vocal function across all experimental groups, with the RMST group showing the greatest improvement, followed by the IMST group, and the EMST group exhibiting the least improvement compared to the control group.
Conclusion: This study provides novel insights into the application effects of various types of RMST interventions for individuals with presbyphonia.