We hypothesized that the ability of the Lung Flute to enhance mucus clearance from the lower airways could be used to improve asthma control, if the device is used on a chronic basis. The primary end point of the study is the comparison of Asthma Control Test (ACT) - a validated questionnaire for asthma control and exhaled NO before, during and after using the lung flute. Several secondary end points were assessed for efficacy and safety, including health status, spirometric lung function, "stepping down" controller therapy and daily albuterol use.