The investigator is examining the use of one airway clearance medical device compared to the use of two airway clearance medical devices together in patients with amyotrophic lateral sclerosis (ALS). More specifically, the investigator wants to know how effective the use of either a mechanical High Frequency Chest Compression (HFCC) device is on its own or the use of both a mechanical High Frequency Chest Compression (HFCC) device and Cough Assist together to maintain a healthy airway and clear secretions.