Review of the impact of voice training on the vocal quality of professional voice users: implications for vocal health and recommendations for further research.

OBJECTIVE: To review the current published available research into the impact of voice training on the vocal quality of professional voice users, to provide implications for vocal health and recommendations for further research.
DESIGN: Literature review with a systematic approach.
METHODS: A systematic search of the literature was conducted using electronic databases and the following defined search terms: occupational voice or occupational dysphonia or voice and occupational safety and health. To obtain the comprehensive relevant literature, no studies were excluded on the basis of study design. In total, 10 studies that investigated the impact of a voice training intervention on the vocal quality of professional voice users as a potential prevention strategy for voice disorders were selected for this review.
RESULTS: The 10 studies ranged in design from observational to randomized controlled trials with mainly small sample sizes (N = 11-60). Nine studies showed that voice training significantly (P < 0.05) improved at least one voice-related measurement from the several investigated from baseline. Five studies reported that voice training significantly (P < 0.05) improved at least one measurement compared with no training.
CONCLUSIONS: Findings indicate that there is no conclusive evidence that voice training improves the vocal effectiveness of professional voice users, as a result of a range of methodological limitations of the included studies. However, some studies did show that voice training significantly improved the knowledge, awareness, and quality of voice. Therefore, there is a need for robust research to empirically confirm this, with implications for vocal health, and occupational safety and health policies.