D stands for Design

Jules Engel (1909-2003) was a very well known animator who worked with relations between sound and vision. He was a part of the group obsessed with creating a link between the senses, blending of the senses if you may say so. 'Silence' was one of his pioneering works towards creating sound through only visuals. The use of motion graphics to produce sound was not previously done and this laid the bricks of a beginning of visual sound.