July 27, 2017

Watch: How 'Dunkirk' Uses a Classic Audio Illusion to Ratchet Up the Tension

The auditory phenomenon known as the Shepard tone is used to add suspense to Dunkirk

When filmmakers use every cinematic element at their disposal, good films can become great, and this isn't just the case for big-budget blockbusters. One filmmaker who has had an intuitive understanding of this principle from his first film is Christopher Nolan, whose current blockbuster Dunkirk uses visuals, music, and even sound itself to shape its story, in the form of the auditory illusion known as the Shepard tone. 

Composer Hans Zimmer and Nolan have enjoyed a fruitful collaboration; their work on Inception made use of one song, manipulated, as a way to link the various pieces of the film, and Interstellar featured a haunting organ score, also by Zimmer. Like many directors, Nolan has an idea of the music and sounds he wants to use long before the start of production. While writing Dunkirk, he began to focus early on the ticking of a watch that he owned: Taping the sound, he sent it to Zimmer, and together, they used this ticking to build out the score and add tension to the film's three interwoven storylines. 

Shepard tones can be hidden inside of a film's sound design to cause effects in an audience that they're not even aware of.

But that's not all. The two also revisited a technique first used by Nolan in 2006's The Prestige (where he worked worked with composer David Julyan.) Known as the Shepard tone, it's an auditory illusion, known for hundreds of years, that consists of "several tones separated by an octave, layered on top of each other." The technique has been used in everything from Bach's Canon, to the Beatles' "I Am The Walrus," and even Mario 64. According to Vox's video, as "the tones move up the scale, the highest-pitched tone gets quieter, the middle pitch remains loud, and the lowest bass pitch starts to become audible." But talking about music, as they say, can be like dancing about architecture, so it's probably better to let you listen: 

Nolan wanted to use these tones to link the stories, to "...build the music on...mathematical principals...there's a fusion of music and sound effects and picture that we've never been able to achieve before.” While the tones seem to be getting higher (they can also seem to descend, of course), in fact they never do, and the effect is capable, if used in a specific way of producing, "anxiety and panic attacks."  

Carefully modulated, Shepard tones can be hidden inside of a film's sound design, much like the infrasound effect I wrote about last month, to cause effects in an audience that they're not even aware of. That being said, Zimmer and Nolan are not trying fool anyone or send them screaming from the theater.

Interested in experimenting? This technique is by no means beyond the reach of the indie filmmaker. This tutorial shows how any DAW (digital audio workstation) is capable of producing the effect, so check it out and see what you can come up with. You can even generate your own tones here with the caveat to exercise caution, particularly if you're susceptible to panic attacks. Basically, just try not to freak yourself (or anyone else) out.      

Your Comment


I really wish that TV and movies would stop overly relying on non-diegetic noise to create mood. I realize that a score can help tie cuts and scenes together, and I think a filmmaker should have license to use everything available to create a mood. For some reason, though, I am especially sensitive to sound and Nolan's audio tricks take me completely out of the movie. I find the sound abrasive and end up focusing entirely on the sound rather than on the story. I think this is why you keep finding stories popping up about how the audience is complaining that Nolan's movies are "too loud" or overwhelm the dialogue. I realize that this is Nolan's artistic choice just like Michael Bay's artistic choice is to have gasoline fueled explosions in everything, but I don't think that Nolan actually understands that his sound choices can actually be overly distracting rather than add to the experience for some people.

July 28, 2017 at 12:28PM

Casey Preston

I agree, I felt as if the track was very strong throughout the movie which took me out of the scenes. I feel as if silence and raw sound would have worked tremendously.

July 28, 2017 at 5:14PM


yes! nice to hear some other people felt the same way. the film was an amazing experience, but I felt like some quiet between would have given it so much more rhythm and tension than a constant barrage. Incredible film though.

July 29, 2017 at 1:40PM

Ricky Norris