The definition of the word “vacuum” helped create the most memorable scene in Star Wars: The Last Jedi. But, director Rian Johnson had to clarify to sound designer Ren Klyce exactly what he meant when he used that word.

On Tuesday, ABC News Features debuted a new documentary called The Force of Sound. Specifically focusing on the sound design for Star Wars: The Last Jedi, the documentary details the organic processes by which several of the sound effects were made for the film.

And one obvious focus of the documentary was a scene in which no sound is heard at all. Both Klyce and Johnson make it clear that for a brief time, they weren’t on the same page as to what a “vacuum” sounded like.

In the documentary, Klyce admits to trying to give Johnson several versions of a “vacuum sound,” and in doing so, imitates a sucking sound, as though he was trying to emulate a vacuum cleaner. This apparently wasn’t quite what Johnson had in mind.

The entire confusion was centered around the difference between a “vacuum” being the absence of sound, or a “vacuum” being a sound effect in it of itself. When Admiral Holdo jumps her ship into hyperspace and destroys a First Order dreadnaught in the film, fans freaked out. But, it was this one sound decision that Johnson was most adamant about.

Because so many of the sounds in Star Wars are based on real, organic things, its somewhat ironic that the most memorable moment from the latest movie actually just throws all that out the window. Just as Luke Skywalker shut himself off from the Force, sometimes, the best sound effect is just to turn everything off entirely.

The Last Jedi will hit Blu-ray on March 27, 2018. You can watch the entire documentary streaming right here.