Synchromy

Synchromy French Synchromie is a 1971 National Film Board of Canada visual music film by Norman McLaren utilizing graphical sound. To produce the films musical soundtrack, McLaren photographed rectangular cards with lines on them. He arranged these shapes in sequences on the analog optical sound track to produce notes and chords. He then reproduced the sequence of shapes, colorized, in the image portion of the film, so that audiences see the shapes that they are also hearing, as sound.

Terence Dobson, The Film Work of Norman McLaren Eastleigh John Libbey Publishing, 2006 ISBN 0 86196 656 2

Source: Wikipedia