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. 2007 Oct 17;2007(4):CD006372. doi: 10.1002/14651858.CD006372.pub2

Comparison 4. Direct and indirect voice training combined versus indirect voice training only.

Outcome or subgroup title No. of studies No. of participants Statistical method Effect size
1 Subjective phonation difficulty 2   Mean Difference (IV, Fixed, 95% CI) Subtotals only
1.1 At end of semester after work day 2 86 Mean Difference (IV, Fixed, 95% CI) ‐5.55 [‐23.75, 12.66]
2 Subjective voice quality 2   Mean Difference (IV, Fixed, 95% CI) Subtotals only
2.1 At the end of semester after work day 2 116 Mean Difference (IV, Fixed, 95% CI) 0.11 [‐14.71, 14.93]
3 Subjective throat tiredness 2   Mean Difference (IV, Fixed, 95% CI) Subtotals only
3.1 At the end of semester after work day 2 116 Mean Difference (IV, Fixed, 95% CI) ‐0.93 [‐9.47, 7.61]
4 Voice quality assessed by 3 vocologists 1 59 Mean Difference (IV, Fixed, 95% CI) 19.0 [‐41.53, 79.53]
5 Firmness of phonation assessed by 3 vocologists 1 59 Mean Difference (IV, Fixed, 95% CI) 16.0 [‐38.32, 70.32]
6 Average fundamental frequency (F0) whilst reading at habitual loudness 1 59 Mean Difference (IV, Fixed, 95% CI) 3.0 [‐5.38, 11.38]
7 Sound pressure level (dB) whilst reading at habitual loudness 1 59 Mean Difference (IV, Fixed, 95% CI) ‐1.0 [‐2.67, 0.67]
8 Alpha ratio (dB) whilst reading in habitual loudness 1 59 Mean Difference (IV, Fixed, 95% CI) 0.30 [‐0.86, 1.46]
9 Jitter (%) 1 59 Mean Difference (IV, Fixed, 95% CI) ‐0.12 [‐0.40, 0.15]
10 Shimmer (dB) 1 59 Mean Difference (IV, Fixed, 95% CI) ‐0.19 [‐0.34, ‐0.05]