Relation between pendulum angle and pressure amplitude or pressure duration in positive and negative pressure. Open circles and open squares indicates pressures generated using a 1 and a 2 kg weight struck with a pendulum, respectively. Panel A is the change in amplitude of positive pressure. Panel B is the change in duration of positive pressure. Panel C is the change in amplitude of negative pressure. Panel D is the change in duration of negative pressure. Results are expressed as the mean ± standard deviation of three independent experiments.