Abstract: A respiratory therapeutic device for actively loosening and breaking up phlegm in a user's lungs and bronchial and tracheal passages while a user is breathing through the device. The device includes a housing containing a base portion and a cap portion forming at least a portion of a sonic coupling chamber having a plurality of breathing holes therethrough and adapted to be held in a patient's mouth. The base portion contains an audio generator behind a sanitary flexible diaphragm separating the portions. The generator preferably includes a power supply and a pulsed audio signal generator connected to the speaker. The audio signal generator may be adjusted by the user as to tone pitch and tone burst repetition rate to optimally loosen accumulated phlegm in the user's lungs during unit operation.