Ever since 1927, when sound was first introduced to cinema, filmmakers have experimented with all kinds of subtle ways to aurally manipulate audiences.
Whether it's dialogue, action, wardrobe, composition or special effects, there's a lot that goes into creating a compelling film. But in modern day cinematography, scoring and sound design are as crucial a factor as any.
Dunkirk director Christopher Nolan, as Sploid explores in a new piece, is so intrigued by sound, he's introduced a so-called "audio illusion" called a Shepard tone into several of his films, including Interstellar, Inception, The Prestige.
The tone, named for psychologist Roger Shepard, is a bit of an audio mind-trick that plays on our need for resolution.
You can hear the Shepard tone above.
The tone is comprised of multiple scales in different musical voices, i.e. treble, mid-range and bass, separated by one octave a piece. The scales ascend or descend continuously and create the dizzying Shepard tone, which seems to swirl around infinitely with no tonal resolution.
Sploid notes that Nolan loves the anxiety the Shepard tone creates. His script-writing has been influences by the tone's "corkscrew effect," and he disclosed to Business Insider that the music in his films borrows aspects from the tone.