Prevalence of Subclinical and Clinical Dysphagia in Parkinson's Disease

"Intervention: After recording the patient characteristics and the baseline dysphagia characteristics, the intervention begins. The intervention lasts 3 weeks, by extended stay it lasts 5 or 7 weeks.~The intervention has two parts. One part of the intervention is the biofeedback therapy. The biofeedback therapy means that the patient and an SLT watch the video of the FEES together and discuss the findings. The other part of the intervention is a swallow training or a voice training. The frequency of therapy is minimum 3 times a week, the duration of one therapy is minimum 25 minutes.~Allocation to the Groups will be done by a randomization software"