[1] Helsinki Univ Hosp, Dept Otorhinolaryngol & Phoniatr Head & Neck Surg, Helsinki, Finland
[2] Univ Helsinki, Doctoral Sch Hlth Sci, Helsinki, Finland
[3] Univ Eastern Finland, Philosoph Fac, Sch Humanities, Dept Logoped, Joensuu, Finland
[4] Univ Helsinki, Fac Med, Dept Psychol & Logoped, Helsinki, Finland
[5] Univ Oulu, Res Unit Logoped, Oulu, Finland
[6] Tampere Univ, Fac Social Sci, Dept Psychol Welf Sci, Tampere, Finland