Shepard Tone: Where Time Loops and Noir Lives Forever

Introduction

Shepard Tone, also known as the "Infinite Tone," is an auditory illusion consisting of overlapping sine waves separated by octaves. This creates a perpetual sensation of a rising or falling tone that never actually reaches a resolution - a continuous loop that plays tricks on our perception. Named after cognitive scientist Roger Shepard, the concept has been widely applied in music, film, and sound design to evoke tension and endless progression.

Inspired by this phenomenon, I conceptualized and directed a crime-noir short film titled Shepard Tone. The film is not just an homage to the auditory illusion but also an experiment in storytelling, time manipulation, and tension building. Shot entirely in black and white, the film unfolds in a single continuous take lasting 22 minutes, set in a semi-constructed building divided into four apartment units with seven characters and a Crime Novelist who tries to finds an End for his novel, through his mind.

Shepard Tone as a Narrative Device

For me, Shepard Tone offered a unique framework to experiment with time in cinematic storytelling. Time has always been a central theme in my work, and the looping nature of Shepard Tone served as the perfect metaphor for a non-linear narrative.

The story is divided into three distinct sections, each representing a different perspective on the same sequence of events leading up to a murder. Instead of following a traditional linear progression, each section starts earlier in time and presents a new angle, effectively looping back without any cuts. This continuous flow mirrors the Shepard Tone’s auditory illusion - a seamless rise and fall that never truly resolves.

Visual and Aesthetic Choices

The decision to shoot the film in black and white was influenced by classic noir aesthetics and my fascination with monochrome minimalism. The Crime Novelist character, inspired by iconic French and American noir films, is portrayed as a timeless observer with a fedora, trench coat, cigarette, and dark glasses. This design choice reinforces the character’s detachment from the temporal flow of the narrative.

In my previous short film I’m A.I, I explored similar minimalistic and noir elements, drawing heavily from the cinematic styles of the 1930s and 1940s. With Shepard Tone, I aimed to elevate these themes by integrating a real-time, long-take approach, creating an immersive and tension-filled experience.

Technical Execution and Challenges

Filming a 22-minute continuous take without cuts was a significant technical and artistic challenge. Every movement, dialogue, and camera maneuver had to be meticulously choreographed to maintain the narrative’s fluidity and coherence. This real-time execution enhances the immersive quality of the film, drawing the audience deeper into the unfolding mystery.

The soundtrack plays a crucial role in sustaining tension. By incorporating a Shepard Tone-inspired score, I aimed to evoke a sense of perpetual suspense. The continuous rise and fall of the tone, much like the film’s looping narrative, keeps viewers on edge, amplifying the psychological impact of the story.

Understanding Shepard Tone: How the Illusion Works

Shepard Tone is created by layering sine waves separated by octaves, with each wave fading in and out at different points. As a result, the tone seems to ascend or descend endlessly without ever reaching a peak or bottom. This auditory illusion can be compared to a barber’s pole - the stripes appear to move continuously upward or downward, even though they are actually looping around the pole.

A conceptual example of an ascending Shepard scale begins with a nearly inaudible C4 (middle C) and a loud C5 (an octave higher). As the scale progresses, the lower tone increases in volume while the higher tone fades out, creating the illusion of a continuously rising pitch. By the time the twelfth tone (B4) is reached, a new, almost inaudible B3 is introduced, and the cycle begins again.

Jean-Claude Risset later expanded on Shepard’s work by creating a continuous gliding version known as the Shepard-Risset glissando. This version enhances the illusion by eliminating discrete steps, resulting in a smoother, more haunting effect.

Examples of Shepard Tone in Popular Media

The Shepard Tone illusion has been creatively employed in various forms of media:

Music:

The Beatles used Shepard Tone in the ending of "I Am the Walrus" to create an eerie, endless descent.

Pink Floyd incorporated an ascending Shepard Tone in the track "Echoes" from their 1971 album Meddle using a feedback loop technique.

Franz Ferdinand featured a rising Shepard Tone throughout their 2018 track "Always Ascending."

Film:

Director Christopher Nolan frequently employs Shepard Tone in his films. In The Dark Knight (2008), the sound of the Batpod uses a Shepard-like engine roar that continuously rises in pitch without changing gears. In Dunkirk (2017), composer Hans Zimmer layered Shepard Tones throughout the soundtrack to sustain tension across the intertwined storylines.

Video Games:

In Super Mario 64, the infamous "endless stairs" sequence uses a modified Shepard Tone to create the illusion that the player is climbing an infinite staircase unless they possess a required number of stars.

Conclusion

My Short Film, Shepard Tone is more than a film - it is an exploration of time, perception, and storytelling. By merging the looping narrative structure with the auditory illusion of Shepard Tone, I sought to create a cinematic experience that challenges viewers’ understanding of continuity and resolution.

This project represents my ongoing quest to push the boundaries of narrative and aesthetic conventions in cinema. Whether through visual design, real-time execution, or sound manipulation, Shepard Tone stands as a testament to the power of experimental storytelling.

I hope to continue exploring such innovative approaches in future works, inviting audiences to question their perceptions and immerse themselves in new dimensions of cinematic art.