Nath, A. R. and Capel, L. H. (1974).Thorax, 29, 695-698. Inspiratory crackles and mechanical events of breathing. Forgacs (1967) has suggested that the timing of individual inspiratory crackles is determined by the elastic tension of the lung. This hypothesis was tested by recording the inspiratory crackles simultaneously with a recording of transpulmonary pressure, inspired volume, and inspiratory flow rate. The timing of an individual crackle was found to be closely associated with a particular transpulmonary pressure.