Inclusion Criteria:  Idiopathic Parkinson-Syndrome according to the Movement Disorders Society Criteria Treatment with bilateral deep brain stimulation in the subthalamic nucleus (for parts 1, 2 and 3) Time since DBS-STN operation ≥ 3 month (for parts 1, 2 and 3) Able to give informed consent as documented by signature Fluent in Swiss-German or German STN-DBS-induced dysarthria. In an operational definition, all PD-patients who reported -worsening of speech time-locked to STN-DBS implantation or patients with dysarthria on chronic stimulation improving with reduction of stimulation amplitudes in the context of postoperative routine follow up will be defined as having STN-DBS-induced dysarthria  Exclusion Criteria:  Dysarthria caused in addition by a condition other than PD or DBS (e.g. stroke, myasthenia) Clinical diagnosis of aphasia Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders and dementia. A Montreal Cognitive Assesment (MoCa) will be performed and patients with ≤ 20 of 30 points will be excluded Change of parkinsonian medication in the last four weeks prior to inclusion in part 1 and 3 Change of STN-DBS parameters in the last four weeks prior to inclusion (for parts 1 and 3) Depression with acute suicidal ideation Pregnant women