"Mr. Spielberg, who with the sound designer Ben Burtt supervised the conversion of “Raiders of the Lost Ark” to Imax, said that no special effects or other visual elements of the film were changed. The audio, he said, had been enhanced for surround sound: “When the boulder is rolling, chasing Indy through the cave, you really feel the boulder in your stomach, the way you do when a marching band passes by, and you’re standing right next to it.”