A respiratory therapy device comprising: a housing defining a primary passageway having a patient interface side; a flow diverter structure maintained by the housing in fluid communication with the primary passageway between the primary passageway and a chamber opposite the patient interface side, the flow diverter structure including a neck region that fluidly connects the chamber and the primary passageway, and a reduced-size passage has an inlet side adjacent the chamber and an outlet side adjacent the primary passageway, wherein the reduced-size passage has a constant diameter; a high frequency pressure port maintained by the housing and connected to a nozzle terminating at a nozzle end fluidly open to the chamber and facing a diverter body positioned between the nozzle end and the reduced-size passage, the high frequency pressure port configured for fluid connection to a source of oscillatory gas flow, and being fluidly associated with the flow diverter structure such that jet flow from the high frequency pressure port impinges upon the diverter body and is directed toward the reduced-size passage; and an entrainment port maintained by the housing and openable to ambient air, the entrainment port being fluidly associated with the flow diverter structure; wherein the device is configured such that flow characteristics of gas flow from the high frequency pressure port are altered upon interacting with the flow diverter structure to create a pressure drop for drawing in ambient air through the entrainment port, the gas flow from the high frequency pressure port and ambient air drawn through the entrainment port are directed through the flow diverter structure in delivering a percussive pressure therapy to the patient interface side of the primary passageway. a housing defining a primary passageway having a patient interface side; a flow diverter structure maintained by the housing in fluid communication with the primary passageway between the primary passageway and a chamber opposite the patient interface side, the flow diverter structure including a neck region that fluidly connects the chamber and the primary passageway, and a reduced-size passage has an inlet side adjacent the chamber and an outlet side adjacent the primary passageway, wherein the reduced-size passage has a constant diameter; a high frequency pressure port maintained by the housing and connected to a nozzle terminating at a nozzle end fluidly open to the chamber and facing a diverter body positioned between the nozzle end and the reduced-size passage, the high frequency pressure port configured for fluid connection to a source of oscillatory gas flow, and being fluidly associated with the flow diverter structure such that jet flow from the high frequency pressure port impinges upon the diverter body and is directed toward the reduced-size passage; and an entrainment port maintained by the housing and openable to ambient air, the entrainment port being fluidly associated with the flow diverter structure; wherein the device is configured such that flow characteristics of gas flow from the high frequency pressure port are altered upon interacting with the flow diverter structure to create a pressure drop for drawing in ambient air through the entrainment port, the gas flow from the high frequency pressure port and ambient air drawn through the entrainment port are directed through the flow diverter structure in delivering a percussive pressure therapy to the patient interface side of the primary passageway.