English: Animation of the sound (over)presure in a pipe open at one end, playing a pure sinusoidal note, harmonic 7 of the fundamental. A standing wave mode, with a node at the open end (right) and an antinode at the closed end (left). The profile has 4 total nodes including the open end; 1.75 full waves or 7 quarter-waves in pipe. This animation was obtained by image processing from File:Standing wave.gif (cropping the rightmost quarter-wave, then adding the axis and pipe outline)