Laukkanen 2009.

Methods	RCT
Participants	89 female primary school teachers, of whom 59 are the same as in Ilomäki 2008 Mean age: 41.1 (SD 8.5) Experience in years, mean: 15.3 (SD 8.8) Mean teaching hours per week: 24.3 (SD 4.4)
Interventions	1) Direct and indirect training (voice training and voice hygiene lecture) (30) Same as in Ilomäki 2008 2) Direct and indirect training (Voice Massage(TM) and voice hygiene lecture) (30) Voice Massage(TM) is a Finnish method developed by massage therapist Leena Koskinen. It consists of manipulation of voice and speech production muscles of the larynx, respiration and articulation. It also includes some vocal and respiratory exercises during manipulation. 3) Indirect voice training (voice hygiene lecture only) (29) Same as in Ilomäki 2008
Outcomes	1) Phonation difficulty, voice quality, throat tiredness 2) Voice quality, firmness of phonation, fundamental frequency (F0), sound pressure level, alpha ratio (the ratio between the spectral energy below and above 1000 Hz), jitter, shimmer
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	"In addition to the lecture, a randomly chosen group of 30 subjects received Voice Massage treatment (VM group) and another group of 30 subjects received Voice Training (VT group)" (p.58)
Allocation concealment?	Unclear risk	No details reported regarding whether allocation was concealed or not
Blinding? All outcomes	Unclear risk	"...perceptual voice analysis performed by three experienced speech trainers from 1‐min text reading samples recorded after the working day" (p. 60). The authors do not report if the evaluators were blinded to the experimental conditions to which the participants had been assigned.
Incomplete outcome data addressed? All outcomes	High risk	Group Ns reported in the article are 3 x 30 but the raw data provided by the authors indicated that there had been drop‐outs. Ns in the raw data were 30 and 27 for the intervention groups and 30 for the control group although in the Ilomäki 2008 study that reported on the same participants stated that one participant had been lost from the control group.
Free of selective reporting?	High risk	In the article, the authors do not report numerical results for their primary self‐reported outcomes. The authors however provided these on request.