Respiratory Muscle Strength Training to Improve Vocal Function in Patients with Presbyphonia

Abstract

The effects of presbyphonia are compounded by the decline in respiratory function that occurs with age. Commonly recommended exercises to optimize the use of respiratory muscles during speech, such as diaphragmatic breathing, are unlikely to be intensive enough to induce respiratory changes and impact vocal function. The objective of this study was to assess the effect of adding a targeted intervention, respiratory muscle strength training, to voice exercises in a sample of patients with presbyphonia. In this prospective, randomized-controlled trial, 12 participants received either (1) vocal function exercises (VFE), (2) VFE combined with inspiratory muscle strength training (IMST), or (3) VFE combined with expiratory muscle strength training (EMST). Data collected prior to and following 4 weekly intervention sessions included respiratory measures (pulmonary function and respiratory muscle strength) and voice measures (videostroboscopy, acoustic, auditory-perceptual, aerodynamic, and self-assessment measures). Participants who received IMST improved their voice quality during connected speech (smoothed cepstral peak prominence and ratings of overall voice quality) and their scores on the three self-assessment questionnaires with large to very large within-group effect sizes (|d|=0.82-1.61). In addition, participants in the IMST group reduced their subglottal pressure with a large effect size (d=-0.92). Participants who received EMST improved their maximum expiratory strength and smoothed cepstral peak prominence with large effect sizes (d=0.80 and 0.99, respectively) but had limited improvements in other outcomes. Participants who received only VFE decreased their amount of vocal fold bowing, improved their voice quality on a sustained vowel (amplitude perturbation quotient), and improved their Glottal Function Index score with large effect sizes (|d|=0.74-1.00). Preliminary data indicate that adding IMST to voice exercises may lead to the greatest benefits in patients with presbyphonia by promoting improved subglottal pressure control as well as increasing air available for phonation, resulting in improved self-assessment outcomes.