Fig. 2: Exemplary signals from in-ear IH headphones and synchronized Lead-II ECG representing one cardiac cycle.

ECG (top, blue) and IH signals from the left (red, middle) and right (red, bottom) ears for nine healthy subjects in the SR sample shown for 20 heartbeats stacked together (dotted lines), along with their mean (solid line) and standard deviation (band). Subjects' heart rate (HR) and the average duration of the cardiac cycle (IBI) are displayed as well.