Graphometric analysis of cough tachogram

The tachogram shows that the flow of cough is neither continuous nor steady. Within a cough, 5 different phases can be differentiated: 1) acceleration, 2) initial fast decleration, 3) intermediary decleration, 4) terminal fast decleration, and 5) the flow-pause. Only in the course of phases 1) and 3) is the air flowing out from the lungs. In cough series the peak-flows of subsequent coughs are growing smaller and smaller. This decrease follows the form of an isosceles hyperbola. A cough can be short or elongated. From the flow-phases the 1-st, 2-nd and 4-th ones are of fairly stable duration. The wide deviation of the intermediary deceleration shows that this phase makes it possible to elongate voluntarily the cough.