The Impact of Semi-Occluded Vocal Tract Exercises on Vocal Function in Singers: Straw Phonation vs. Lip Trill

Abstract

Singing and acting teachers have used semi-occluded vocal tract exercises (SOVTs) for many years to help elicit easier and more efficient vocal production. There is limited research on SOVTs and the application to singers. Straw phonation and lip trills are two of the more common SOVTs utilized. The purpose of this study was to assess the outcomes from lip trill versus straw phonation exercises with adult singers. The study is designed to assess whether lip trill produces as much change as that induced by straw phonation. The primary outcome measures were singing voice-related quality of life as measured by the Singing Voice Handicap Index (SVHI), singer’s perceived physical functioning of their voice as indexed by the Evaluation of the Ability to Sing Easily (EASE), and auditory-perceptual ratings of overall voice quality on the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). There were fourteen professionally trained singers in two groups, straw phonation and lip trill. They completed 21 days of exercise with either straw phonation or lip trill completed four times a day in five minute increments spread across the day. They had one meeting a week for a total of three meetings with study personnel who reviewed their completion of the exercises. A 2 x 2 (Time: Pre- vs. Post-exercise; Group: straw phonation vs. lip trill) analysis of variance revealed a statistically significant main effect of Time but not Group for ratings of the physical functioning of the voice (EASE). The interaction effect was not significant. The direction of the change on the EASE indicated a perceived improvement in physical functioning of the voice after completing SOVT exercises. The main and interaction effects for the SVHI were not significant. Ratings from the CAPE-V had unacceptable listener reliability so analysis was not performed on these data. The results suggested that EASE scores improved after three weeks of an SOVT, and there was no difference between the two SOVT groups. Additional study is required to determine optimal dosing and to further explore the acoustic and physiological changes that coincide with the self-rated changes in physical functioning of the voice.