Faculty of Humanities, Research Unit of Logopedics, University of Oulu, Oulu, Finland; PEDEGO Research Unit, University of Oulu, Oulu, Finland; MRC Oulu, Oulu, Finland; Department of Otorhinolaryngology, Head and Neck Surgery, Oulu University Hospital, Oulu, Finland. Electronic address: kerttu.huttunen@oulu.fi.