1. PEDEGO Research Unit, University of Oulu, Oulu, Finland
2. Medical Research Center Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
3. Department of Otorhinolaryngology and Head and Neck Surgery, Oulu University Hospital, Oulu, Finland
4. Division of Operative Care and Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
5. Thule Institute, University of Oulu, Oulu, Finland
6. School of Medical Sciences, Örebro University, Örebro, Sweden
7. Audiological Research Centre, Örebro University Hospital, Örebro, Sweden