Inclusion Criteria:  Diagnosis of idiopathic, typical Parkinson disease. Modified Hoehn and Yahr stages 1-3 per physical exam. Able to walk independently without physical assistance or an assistive device.  Exclusion Criteria:  Diagnosis of atypical Parkinsonism. Moderately or significantly disturbing freezing episodes during daily walking. Cognitive impairment as determined by the Montreal Cognitive Assessment (MoCA). Significant hearing impairment. Currently participating in physical therapy. Cardiac problems that interfere with the ability to safely exercise. Orthopedic problems in the lower extremities or spine that may limit walking distance.