1Otolaryngology-Head and Neck Surgery and
2Clinical Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
3Department of Otolaryngology and Communication Disorders, University of Antwerp, Edegem, Belgium
4Speech Therapy Department, Escola Superior de Saude do Alcoitao, Lisbon, Portugal
5Department of Logopedics and Phoniatrics, Karolinska Institute, Karolinska University Hospital, Huddinge, Sweden
6Department of Phoniatrics and Pedaudiology, University of Greifswald, Greifswald, Germany
7Department of Otolaryngology-Head and Neck Surgery, University of Pittsburgh Voice Center, Pittsburgh, Pa., USA
8Department of Clinical Sciences ‘L. Sacco’, University of Milan, Milan, Italy
9National Hospital for Neurology and Neurosurgery, London, UK
10Department of Otorhinolaryngology, Head and Neck Surgery, Larrey University Hospital of Toulouse, Toulouse, France