1. Hospital Alvarez Buylla; ENT Department; Murias s/n Mieres Asturias Spain
2. Brigham and Women's Hospital, Massachusetts General Hospital; Department of Surgery - Otolaryngology; 75 Francis Street Boston MA USA 02115
3. Johns Hopkins Bloomberg School of Public Health; Department of Epidemiology; Room W6138 615 N. Wolfe St. Baltimore Maryland USA 21205
4. Faculty of Brain Sciences, University College London; Ear Institute; London UK