Vocal Function Exercises With and Without Maximally Sustained Phonation: A Randomized Controlled Trial of Individuals With Normal Voice

Objectives: To determine the effect of maximally sustained phonation on efficacy of Vocal Function Exercises as measured by percent of maximum phonation time goal attained. The hypothesis was that maximally sustained phonation would result in greater improvements in percent of maximum phonation time goal attained. Study Design: Randomized controlled trial. Methods: A convenience sample of individuals with normal voice were recruited in a university academic clinic setting. Of 34 participants who volunteered for the study, 31 completed baseline assessment and 23 completed all study procedures. Participants were randomized to complete Vocal Function Exercises (traditional group TG), modified Vocal Function Exercises with reduced requirement for maximally sustained phonation (midpoint group MG), or modified Vocal Function Exercises with removed requirement for maximally sustained phonation (baseline group BG). The primary outcome measure was percent of maximum phonation time goal obtained during Vocal Function Exercises. Results: The MG (p = 0.008) and TG (p = 0.001) groups significantly improved percent of maximum phonation time goal attained after six weeks of exercise, while the BG group (p = 0.0202) did not (ɑ = 0.0125). Difference among groups was not statistically significant (p = 0.67, ɑ = 0.0125). Hedges’ g effect sizes of 0.29 (-0.66, 1.25) and 0.51 (-0.57, 1.58) were obtained comparing MG and TG groups, and BG and TG groups, respectively. Conclusions: Greater requirements for maximally sustained phonation improved efficacy of Vocal Function Exercises in enhancing normal voice as measured by percent of maximum phonation time goal attained. Maximally sustained phonation may be modified to some extent while preserving efficacy of Vocal Function Exercises, however complete elimination of maximally sustained phonation may attenuate improvement. Additional research in a clinical population is warranted.