Comparison 1. Direct voice training versus no intervention.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Any voice handicap	3		Std. Mean Difference (IV, Fixed, 95% CI)	Subtotals only
1.1 Post‐intervention	3	110	Std. Mean Difference (IV, Fixed, 95% CI)	0.27 [‐0.12, 0.66]
1.2 Follow up	1	24	Std. Mean Difference (IV, Fixed, 95% CI)	0.38 [‐0.44, 1.20]
2 Amount of vocal misuse behaviours	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
2.1 Post‐intervention	1	24	Mean Difference (IV, Fixed, 95% CI)	64.73 [‐65.48, 194.94]
2.2 Follow up	1	24	Mean Difference (IV, Fixed, 95% CI)	53.99 [‐73.58, 181.56]
3 Normalised maximum phonation time (seconds)	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
3.1 Post‐intervention	1	24	Mean Difference (IV, Fixed, 95% CI)	3.32 [‐0.53, 7.17]
3.2 Follow up	1	24	Mean Difference (IV, Fixed, 95% CI)	3.17 [0.24, 6.10]
4 Maximum phonational frequency range	1		Mean Difference (IV, Fixed, 95% CI)	Subtotals only
4.1 Post‐intervention	1	24	Mean Difference (IV, Fixed, 95% CI)	‐0.05 [‐4.59, 4.49]
4.2 Follow up	1	24	Mean Difference (IV, Fixed, 95% CI)	‐1.03 [‐5.04, 2.98]