(A) Representative example of an average sonR cycle composed of 15 consecutive, ensemble-averaged cycles (B). The same average sonR cycle, high-pass filtered, and its envelope in doted gray line. The vertical markers are the detected components of sonR1 and sonR2, including, consecutively (1) t_{sonR1_onset}, (2) t_{sonR1_end}, (3) t_{sonR2_onset}, and (4) t_{sonR2_end}. t = 0, the onset of the cardiac cycle, is the pacing artefact or the QRS onset marker. (C) Average electrocardiographic signal composed of 15 consecutive, ensemble-averaged cycles.