Move a point around a closed shape at constant speed and plot only its height against time. A circle gives a pure sine. The heart gives two bumps and one long dip, the astroid gives flat, sharp peaks, the five point star adds five ripples, and the lemniscate, a figure eight, crosses zero four times per turn. All five repeat every 1.4 seconds, so only the shape of the wave changes. A higher point is a higher note.