Figure 2: Software-derived variables of swallowing function. To operate analysis software, the analyst opened a colour pressure isocontour plot of each swallow file. Analysts then defined four space-time landmarks on the plot (white crosses). Guided by definition of these landmarks, the software then automatically generated values for swallow function variables measuring contractility (PhPP, hPP, and PhCI), intrabolus distension pressure guided by maximum admittance/nadir impedance (PhIBP, hIBP), flow timing (PhDCL, hDCL), and bolus presence (hFI).