Fig. 3— Voluntary coughs and a cough epoch in a female subject. Traces, from the top: time in s, cough sound, airflow (expiration upwards), thoracic/oesophageal pressure (positive upwards), and abdominal pressure (positive upwards). On the left are two voluntary coughs. They are followed by a spontaneous involuntary cough epoch consisting of an initial inspiration and then four compressive and expulsive phases without intermediate inspirations. Vertical lines indicate equal time points. Exp: expiration.