1. Conservative Dentistry and Periodontology Department, Karol Marcinkowski University of Medical Sciences, Poznań, Poland;
2. Vocal Department, Ignacy Jan Paderewski Academy of Music, Poznań, Poland;
3. Spine Surgery Oncological Orthopaedic and Traumatology Clinic, Karol Marcinkowski University of Medical Sciences, Poznań, Poland;
4. Department and Clinic of Maxillofacial Orthopaedics and Orthodontics, Karol Marcinkowski University of Medical Sciences, Poznan, Poland;
5. Department of Phonetics and Audiology, Karol Marcinkowski University of Medical Sciences, Poznań, Poland