The illusion of sound traveling across the speakers was achieved with a device named the "pan pot", which directed the predetermined movement of each audio channel with the control track. Mixing of the soundtrack required six people to operate the various pan pots in real time, while Stokowski directed each level and pan change which was marked on his musical score. To monitor recording levels, Disney used oscilloscopes with color differentiation to minimize eye fatigue. To test recording equipment and speaker systems, Disney ordered eight electronic oscillators from the newly established Hewlett-Packard company. Between the individual takes, prints, and remakes, approximately three million feet of sound film was used in the production of Fantasia.It's perhaps a different measure, but Disney's technicians elsewhere wrote that the production "excluding release prints, required the use of five million feet of film!" (Garity, Wm. E. and Hawkins, J.N.A., "'Fantasound': A Technological Epoch." International Projectionist, August 1941, 16. Almost a fifth of the film's budget was spent on its recording techniques.
