ABSTRACT
BACKGROUND: To date, the immediate effects of a semi-occluded vocal tract (SOVT) configuration have been thoroughly demonstrated. However, it is not yet sufficiently confirmed whether a therapy programme (i.e. longer than one session) using SOVT exercises leads to an enhanced phonation and improved vocal quality. AIMS: The aim of this study was to investigate the effect of three SOVT therapy programmes: lip trill, water-resistance therapy (WRT) and straw phonation, on the vocal quality, vocal capacities, psychosocial impact and vocal tract discomfort of patients with dysphonia. METHODS & PROCEDURES: A blocked-randomized sham-controlled trial was used. Thirty-five patients with dysphonia (mean age = 21 years; 33 women, two men) were assigned to either a lip trill group, a WRT group, a straw phonation group or a control group using blocked randomization. The lip trill, WRT and straw phonation groups practised their respective SOVT exercise across 3 weeks, whereas the control group received a sham treatment across the same time span. A multidimensional voice assessment consisting of both objective (multiparametric indices: Dysphonia Severity Index (DSI), Acoustic Voice Quality Index (AVQI)) and subjective (subject's self-report, auditory-perceptual evaluation) vocal outcomes was performed by a blinded assessor pre- and post-therapy. OUTCOMES & RESULTS: Lip trill and straw phonation therapy led to a significant improvement in DSI. Auditory-perceptual grade and roughness significantly decreased after straw phonation. Lip trill and WRT both led to a significant decrease in Voice Handicap Index. Subjects reported a better self-perceived vocal quality and a more comfortable voice production after WRT. No changes were found after the sham treatment in the control group. CONCLUSIONS & IMPLICATIONS: Results suggest that SOVT therapy programmes including lip trill or straw phonation can improve the objective vocal quality in patients with dysphonia. Auditory-perceptual improvements were found after straw phonation therapy, whereas psychosocial improvements were found after lip trill and WRT. Patients seem to experience more comfort and a better self-perceived vocal quality after WRT. This study supports the use of the three SOVT therapy programmes in clinical practice. They all had a positive impact on one or more outcomes of the multidimensional voice assessment. Strikingly, vocal quality outcomes were not in line with the subject's opinion. Larger-scale investigation is needed to support these preliminary findings.
