A method of providing airway clearance therapy to a patient includes receiving an expiratory airstream from the patient in a chamber, causing a back pressure to be created in the chamber (10) in response to receiving the expiratory airstream, causing a one-way valve, such as a magnetic duckbill valve (26), located downstream of the chamber to open only in response to the back pressure being at least equal to a certain predetermined level, causing a vibratory effect to be generated downstream of the one-way valve, for example using a vibratory ball check valve (32), when the one-way valve is open and in response to the expiratory air-stream passing therethrough, and delivering a percussive sensation to the patient through the chamber responsive to the vibratory effect.
