[1] Univ Sydney, Fac Hlth Sci, Australian Stuttering Res Ctr, Sydney, NSW, Australia
[2] Univ Queensland, Sch Publ Hlth, Brisbane, Qld, Australia
[3] Griffith Univ, Menzies Hlth Inst Queensland, Nathan, Qld, Australia
[4] Murdoch Children Res Inst, Melbourne, Vic, Australia
[5] Univ Technol Sydney, Australian Stuttering Res Ctr, Bldg 1,15 Broadway, Ultimo, NSW 2007, Australia
[6] Bond Univ, Biostat, Gold Coast, Australia