Arena with two distinct chambers, each associated to a distinct background sound. Play the background sound when the mouse is inside either chamber.
The two chambers are defined as separate ROIs using the CropPolygon node. When the mouse enters the ROI, the average brightness of the ROI decreases. When the average brightness drops below a threshold (manually set in the LessThan node), the sound playback is triggered. The playback is repeated in loop until the brightness goes back above the threshold (== mouse exits the ROI).
DistinctUntilChanged node makes propagate the signal only when there is a change, so either a rising edge (0->1) or falling edge (1->0). The distinction between the two edges is then done by the isTrue and isFalse conditions.
