1. Jan Biziel University Hospital No. 2 in Bydgoszcz, Poland
2. Antoni Jurasz University Hospital No. 1, Bydgoszcz, Poland
3. Department of Otolaryngology, Medical University of Gdansk, Poland
4. Oto-Ryno-Laryngosurgery Clinic, Institute of Physiology and Pathology of Hearing, Kajetany, Poland