Dunkirk (2017) (Dunkerque is a city in France) is a war film written, co-produced, and directed by Christopher Nolan. The script, told from three perspectives (land, sea, and air). The film portrays the Dunkirk evacuation (Operation Dynamo) of the World War II. Also there’s an earlier movie in 1958.

The Miracle of Dunkirk, was the evacuation of Allied soldiers during WWII from the beaches and harbour of Dunkirk, in the north of France, between 26 May and 4 June 1940.

Another great film of Nolan but this has something better: the sound. Hans Zimmer is in charge and he use the auditory illusion of a Shepard tone, which had previously been explored in Nolan’s 2006 film The Prestige. This was coupled with the sound of a ticking clock, that of Nolan’s own pocket watch, which he recorded and sent to Zimmer to be synthesised.

A Shepard tone (sound here), named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower.

We now very well this sound because it cause some anxiety. Remember the endless stairs in Mario 64? The Shepard tone is capable of evoking disruption of equilibrium, frequently leading to the associated feeling of falling. This is why you feel anxiety all the movie, and Nolan and Zimmer knows it.