Charging Time (충전시간)

Dankook University Music Technology annual performance | November 6, 2026, Seogyo Square

Morphogenesis
Morphogenesis (形態形成) · Program note

Work: Charging Time (충전시간)
Team: RC
Members: Park Seyeong (박세영), Lim Jitaek (임지택)
Format: Interactive audiovisual performance

01 About the work

Living forms develop without a blueprint. Each cell simply responds to its neighbors' states, yet those responses accumulate into patterns and structures. This work brings that process to the stage. An electrical change occurring when a performer's body touches a circuit becomes the first signal. Through the survival and death rules of cellular automata, the signal grows into images and sound. The living body and rules: the work is the process by which these different materials come together into a single form.

02 Musical content

In this piece, technology is an instrument, and music is the question of what to communicate through that instrument. We aim to present the process by which a sound acquires form. The piece is a single movement of approximately 10 minutes, performed live on stage rather than played back as a finished recording.

Sonic materials
There are two materials. One is a sustained tone created by contact. It sounds only while a body is connected to the circuit. As the number of connected people changes, tones are added or removed, establishing the harmonic foundation of the piece. The other material is the sound generated by cellular automata. The distribution of living cells determines pitch and rhythm: more cells make the notes denser; fewer cells scatter them more sparsely. A change in the rules changes the musical figure itself.

Sound from the body is slow and continuous; sound from the rules is fast and discontinuous. The way these two contrasting sounds support and push against one another creates the tension of the piece.

Structure
I. Generation
The piece begins in silence. When one person touches the antenna, a single sustained tone emerges, with notes generated by a few cells placed slowly above it. The long spaces between notes make them sound more like points than a melody.

II. Differentiation
When the second person connects, the sustained tone branches into harmony and the cellular automaton's rhythm enters fully. Each change in the rules alters rhythmic density and timbre, dividing one musical figure into several strands of variation. This is the longest and most changeable section of the piece.

III. Emergence
As the two materials begin to alter each other's values, patterns that neither performer has directly written become audible. At the point of greatest sonic density, the performers release their hands. The sustained tone disappears, and the sounds of the remaining cells subside, bringing the piece to an end.

Performance
The two performers agree on sections and transitions rather than notated pitches. Within those boundaries, they listen to one another and improvise the timing and duration of contact and their choice of rules. Details therefore differ from one performance to the next, while the overall progression from generation to emergence remains. Since joining and releasing hands directly marks the music's beginning and end, the audience can visually trace where the sounds originate.

03 Technical content

1. Arduino — Capacitive contact sensing
Two pins are connected through a high-value resistor, and the time required for an electrical signal from the sending pin to reach the receiving pin is measured. When a person's body touches the antenna connected to the receiving pin, capacitance (C) increases through the body's contribution. Charging time (T) increases according to the following relationship. This delay provides the contact data.

T = R × C (T: charging time, R: resistance, C: capacitance)

If resistance is too low, charging finishes too quickly regardless of contact, making the values difficult to distinguish. A resistance of at least 1 MΩ was therefore necessary. In practice, the difference relative to the body's resistance was insufficient, producing only a small change between contact and no contact. Increasing the resistance to 2–3 MΩ resolved this. Fluctuations caused by dry skin or an inconsistent contact area were addressed by securing flexible conductive materials, such as solder wire, to the body in the form of rings or bracelets. In Max, measured values are divided into ranges according to the number of people connected and used to switch functions on and off.

2. Max/MSP/Jitter — 2D cellular automata
Cellular automata model morphogenesis and the mechanisms of survival and death through discrete mathematics. We considered them a particularly direct way to visualize the performance's theme. Because Max's built-in jit.conway supports only a fixed rule (B3/S23), we implemented the calculations ourselves in jit.gen so that the rules could change.

1) The current cell state is sent from jit.matrix to jit.gen to calculate the next generation.
2) The rules are set by two sets of nine toggles specifying birth and survival conditions. Widely used rules are saved as presets.
3) The calculation result is rendered in a window and simultaneously stored in [jit.matrix @thru 0] without being passed onward.
4) When triggered by bang or metro, the stored state is fed back into jit.gen to repeat the process.

We also added a section that displays only cells whose color values exceed a threshold in a video file or live camera input, allowing interaction with external images.