'lautbild' in it's literal sense describes the two works volume and sign of the sine. deviating from it's use in semiotics the two german words 'laut' (eng. loud / sound) and 'bild' (eng. picture / image) hint to the functioning of these pictograms.
a frequency below the human hearing range played back at maximum volume visually moves the membranes of several loudspeakers. through their arrangement two pictograms