1. Department of Communication Sciences and Disorders, Idaho State University Health Sciences, Meridian, ID, USA
2. Department of Speech, Language, and Hearing Sciences, University of Texas, Austin, TX, USA
3. Centre for Augmentative and Alternative Communication, University of Pretoria, Pretoria, South Africa
4. Department of Speech, Language, and Hearing Sciences, Texas Tech University Health Sciences Center, Lubbock, TX, USA
5. Department of Communication Sciences and Disorders, Northeastern University, Boston, MA, USA
6. Center for Communication Enhancement, Boston Children’s Hospital, Waltham, MA, USA