This film demonstrates the experiments that Rudolf Pfenninger carried out at the start of the 1930s, which involved the production of synthetic sounds using the optical sound method. This method made it possible for the first time to store sounds and images on the same film material by photo-optically recording sound waves on the soundtrack at the edge of the filmstrip. After explaining the physical characteristics of sound and the technical procedures for recording it, Pfenninger sets out his approach, in which he first isolated the graphic forms of individual sounds using an oscilloscope, then drew them on a strip of paper, filmed them and transferred them to the optical soundtrack. In conclusion, he demonstrates the new, fantastic sounds thus produced, contrasting them with the patterns of the jag handwriting upon which they are based.