The stored fundamental or natural oscillations are transformed and partially amplified and mirrored respectively by Pursanova TM. The overlaying of oscillations is called interference. The mathematical result of natural oscillation and interfering oscillation will be zero if they are 180° phase-delayed and both have the same phase and amplitude. Resonance means that the amplitude of the natural oscillation is boosted by laying an additional in-phase oscillation onto the natural oscillation.
What can be done with resonance oscillations is well known. For instance, a bridge will start to vibrate more and more if subjected to its resonance oscillation which may ultimately lead to the collapse of the bridge.

Since the blue and the green line are in phase opposition (they cross the x-axis in the same spots but then "valley" and "peak" are on the opposite side of it) the amplitudes are subtracted. In this case the amplitudes are identical, so that the resultingred curve has no amplitude.
The red line results from adding the blue and green lines.Since blue and green pass through the x-axis in the same points and the peaks are shown in the same direction (which means they are in phase) the amplitude of the resulting redline increases throughout.