Inspiratory and expiratory flow rates measured over the time course of a coughing event. The figure displays inspiratory and expiratory flow rates measured over the time course of a coughing event. The inspiratory phase of coughing is when an inspiratory maneuver expands the lung volume for sufficient expiratory power. The second, compressive, phase entails narrowing or complete closure of the glottis that allows pressure to build up. During the brief closure, there is isovolume (i.e., no flow) contraction of the chest wall against a closed glottis. During the expulsive phase, there is glottal opening and the explosive release of a burst of air with expiratory cough rejoinders. There is the characteristic cough sound during the latter maneuver.