Main results
Three studies found similar self-reported vocal symptoms between those who attended direct voice training and those who were in a
no intervention control group (standardised mean difference (SMD) 0.27; 95% CI -0.12 to 0.66).
Two studies found similar self-reported vocal symptoms between those who attended indirect voice training and those who were in a
no intervention control group (SMD 0.44; 95% CI -0.03 to 0.92).