processes widely used today, including simultaneous multitrack recording, overdubbing, and noise reduction. Fantasound, developed in part by Disney engineer William Garity, employed two projectors running at the same time. With one containing the picture film with a mono soundtrack for backup purposes, the other ran a sound film that was mixed from the nine tracks recorded at the Academy to four: three of which contained the audio for the left, center, and right stage speakers respectively, while the fourth became a control track with amplitude and frequency tones that drove variable-gain amplifiers to control the volume of the three audio tracks. In addition were three "house" speakers placed on the left, right, and center of the auditorium that derived from the left and right stage channels which acted as surround channels. As the original recording was captured at almost peak modulation to increase signal-to-noise ratio, the control track was used to restore the dynamics to where Stokowski thought they should be. For this, a tone-operated gain-adjusting device was built to control the levels of each of the three audio tracks through the amplifiers. 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. Almost a fifth of the film's budget was spent on its recording techniques. Release history Theatrical runs 1940–1941 roadshows with Fantasound RKO balked at the idea of distributing Fantasia, which it described as a "longhair musical", and believed its duration of two hours and five minutes plus intermission was too long for a general release. It relaxed its exclusive distribution contract with Disney, who wanted a more prestigious exhibit in the form of a limited-run roadshow attraction. A total of thirteen roadshows were held across the United States; each involving two daily screenings with seat reservations booked in advance at higher prices and