Purpose. The purpose of this study was to examine the short- and longer-term effects (3 months follow-up) of a one-month intensive straw phonation (SP) therapy on the voice quality and voice-related quality of life of female speech-language pathology (SLP) students with mild dysphonia.

Method. Thirty-two female SLP students (mean age: 18.5 years, range: 17.8-19.8 years) with mild dysphonia were included in this study. A randomized controlled trial was used with three experimental groups and a control group. The experimental groups received a short-term intensive voice therapy of one month with SP in air (n = 8), SP in 2cm water (n = 8) or SP in 5cm water (n = 8). The control group (n = 8) received a comparable voice therapy program by using [u] phonation with similar soft onset and slightly pursed lips as in SP but without a straw. Three maintenance sessions were provided via telepractice in the next month. A multidimensional voice assessment was performed immediately before therapy (pre), immediately after therapy (post 1) and at 1 month (after the maintenance therapy = post 2) and 3 months follow-up (post 3) by an assessor blinded to the group assignment and study phase.

Results. Primary outcomes: A significant increase (improvement) in Dysphonia Severity Index (DSI) was found in the SP in 2cm water group between post 1 and post 2. Trends of improvement were visible in the DSI scores between pre and post 1 in the SP in air group, and between pre/post 1 and post 2 in the SP in 5cm water group. A clinically relevant decrease (improvement) in Acoustic Voice Quality Index (AVQI) could be found between pre and post 1 in the SP in 2cm water group. Secondary outcomes: The SP in 2cm water group further showed a significant increase in highest intensity between pre and post 1/post2, a significant decrease in lowest frequency between pre and post 3, and a significant decrease in Vocal Fatigue Index between pre and post 1/post 2. The SP in air group showed an increase in highest frequency between pre and post 2. The SP in 5cm water group showed improvements in the auditory- perceptual parameters roughness and strain between pre and post 1.

Conclusions. Positive effects were found for the three SP interventions. The most promising results were found for SP in 2cm water, suggesting an optimal impedance match between the glottis and the vocal tract in this specific population of female SLP students with mild dysphonia.