 Sound editor Ben Burtt, who had helped create many of the signature sounds from "Star Wars" the year before, also added to the film's ambience.Natural sounds that mix with the city's more industrial noises give way to just the latter as the film progresses.Among them are the grinding noises of garbage trucks, a common urban sound that slowly becomes horrific as it becomes clear that most of what they are processing is the discarded husks that remain of pre-pod human bodies.