PD patients will be enrolled in the study in Aix-en-Provence (N = 60) and Lisbon (N = 60). Their global motor disability will be assessed with dedicated clinical rating scales, without (off) and with (on) pharmacological treatment. Two groups of 60 healthy age-matched volunteers will provide the normal reference for between-group comparisons. Along with the off and on medication clinical examinations, several speech tasks will be recorded. Moreover, speech organ functions will also be assessed during the same examination. The psychosocial impact of dysarthria will be evaluated via self-questionnaires; it will be analysed a posteriori, as well as the speech intelligibility evaluation, and both will strengthen the overall speech assessments. This global investigation will represent a unique opportunity to provide the most precise and reliable description of PD patients' speech and its impacts on intelligibility and quality of life. Challenging and interdisciplinary aspects are combined in our project, which original cross-linguistic approach involves an international collaboration definitely new in the field of motor speech disorders.