Abstract: The invention relates to a system and method for the exploration of the intrathoracic ventilatory mechanism which employs a signal y formed according to the equation: ##EQU1## IN WHICH V is the volume displaced in the mouth, dV/dt is the first derivative of V with respect to the time, Pp is the pleural pressure given by an oesophageal gas-bag, and .lambda..sub.1, .lambda..sub.2, .lambda..sub.3 are three adjustable parameters. The signal y is displayed on an oscilloscope as a loop which is a function of the volume V, and potentiometers corresponding to .lambda..sub.1, .lambda..sub.2, .lambda..sub.3 are adjusted to determine the value of the parameters. First, the potentiometers for .lambda..sub.2 are adjusted to cause the loop to close in a straight line, then the potentiometers for .lambda..sub.1 are adjusted until this straight line is horizontal, and subsequently the potentiometers for .lambda..sub.3 are adjusted until this straight line lies over the x axis.