1. Department of Otorhinolaryngology, IRCCS Policlinico San Matteo Foundation and University of Pavia, Italy;
2. MEDEL GmbH, Innsbruck, Austria;
3. SS Otoprotesica, Implanting Center Regione Piemonte, Ospedale Civile SS Antonio and Biagio e C. Arrigo, Alessandria, Italy