1. Department of Otorhinolaryngology/Head & Neck Surgery; University of Groningen; University Medical Center Groningen; Groningen The Netherlands
2. Cancer Research Center Groningen; University of Groningen; Groningen The Netherlands
3. Department of Mathematics and Computer Science; Eindhoven University of Technology; Eindhoven The Netherlands
4. Department of Otorhinolaryngology/Head & Neck Surgery; Maastricht University Medical Centre; Maastricht The Netherlands
5. Department of Otorhinolaryngology/Head & Neck Surgery; Iuliu Hatieganu University of Medicine and Pharmacy; Cluj-Napoca Romania
6. Department of Phoniatrics, Speech and Swallowing; Ear, Nose and Throat University Hospital; Medical University of Graz; Graz Austria
7. Department of Otorhinolaryngology; Greater Poland Cancer Centre; Poznań Poland
8. Pediatric Otolaryngology; Hospital Infantil del Estado de Chihuahua; Chihuahua Mexico
9. Department of Otorhinolaryngology - Head and Neck Surgery; Helsinki University Central Hospital and University of Helsinki; Helsinki Finland
10. Department of Otolaryngology - Head and Neck Surgery; Poznań University of Medical Sciences; Poznań Poland
11. Klinik für Hals-, Nasen-, Ohrenkrankheiten; Plastische Operationen, Klinikum-Stuttgart; Stuttgart Germany
12. Consulta d'ORL, foniatria i logopèdia; Hosp. Gral de Catalunya (Sant Cugat del Vallès); Barcelona Spain
13. Department for Hearing Speech and Voice Disorders; Medical University Innsbruck; Innsbruck Austria