1. Faculty of Medicine and Health Sciences Physiotherapy Division, Department of Health and Rehabilitation Sciences Stellenbosch University Stellenbosch South Africa
2. Research Unit iDN––Interdisciplinary Developmental Neuroscience, Division of Phoniatrics Medical University of Graz Graz Austria
3. Faculty of Medicine and Health Sciences Department of Psychiatry, Stellenbosch University Stellenbosch South Africa
4. Biostatistics Unit South African Medical Research Council Parow South Africa
5. Statistics and Population Studies University of the Western Cape Cape Town South Africa