Usually 6 track magnetic 70mm sound had two additional speakers behind the screen (for five total) and a mono surround channel (spread throughout the auditorium). A few newer 70mm tracks allocated the additional screen channels to stereo surround duty and the sixth channel as a "baby boom"...
Fantasound for the 1941 premiere gala release of Fantasia. At the very least credited as the first feature film with multi-track surround sound. Walt Disney and his team used to be the ones who set the pace and other's followed. Speaking of pioneering, there were a handful of films from...