Chromagram Methodology
Sound-Driven Wall Design for Station 60
Station 60 is a large-scale architectural installation comprising 530 individually designed panels arranged across four horizontal bands on a 26-metre wall. The visual content of every panel is derived directly from the acoustic analysis of four selected musical works, using chromagram-based spectral decomposition to translate audio into colour, shape, and spatial patterns.
Overview
The Chromagram Station 60 software performs real-time and offline spectral analysis of audio files, converting acoustic energy into a visual representation that can be mapped onto physical panel configurations. The process follows a structured pipeline:
- Audio Assignment — Each of the four wall bands is assigned one of the four commissioned compositions.
- Cue Point Distribution — The timeline of each composition is divided into cue points, each representing the temporal anchor for a group of panels. The number of cue points corresponds to the panel count divided by 7 (the maximum panel subdivisions).
- Spectral Analysis — At each cue point, four parallel analysis systems extract different acoustic features: Pitch, Rhythm, Intensity, and Density.
- Bin-to-Shape Mapping — The 12 chromagram bins are mapped through a configurable "patch cord" system to one of 7 panel types, each with a distinct shape profile and colour.
- Rendering — The final chromagram image composites all four bands at their true proportional scales, producing a blueprint for the physical wall installation.
The Four Compositions
Each composition is assigned to a specific band on the wall, from top to bottom.
C04 — Slow Blinking Streetlight
by Maxwell Mollica
An atmospheric electronic piece with slowly evolving textures and rhythmic pulses that mimic the cadence of a streetlight's intermittent glow. The composition balances ambient pads with percussive elements.
C03 — Long Night Chorale
by Professor Deborah Cheetham Fraillon
A choral work that layers vocal harmonics into rich, sustained tonal fields. The piece explores the depth of human voice through overlapping pitches and resonant intervals that shift gradually over time.
C02 — Lagoon Vignettes
by Jessica Foreman
A series of musical sketches inspired by coastal soundscapes. Each vignette captures a different aspect of water, wind, and organic movement through melodic fragments and timbral variation.
C01 — Skyscrapers
by Alex Bensönn
An energetic composition that evokes the verticality and dynamism of urban architecture. Layered synthesizer lines and rhythmic structures build upward in intensity, reflecting the scale and density of a city skyline.
Composition Selection
Of 12 compositions submitted by Sydney Conservatorium of Music undergraduate students, three works were selected by lecturers in Contemporary Music Practice, Composition for Creative Industries and Digital Music Composition. An additional work was provided by Professor Deborah Cheetham Fraillon to represent the traditional owners of the land where Parramatta is located.
Professor Deborah Cheetham Fraillon, Yorta Yorta woman, soprano, composer and educator has been a leader and pioneer in the Australian arts landscape for more than 25 years.
For over 60,000 years, Parramatta has been home to the Baramadagal and other Dharug peoples, who have cared for the land, waters, and wildlife.
Student Brief
"Please give a 100–200 word overview of your piece, what themes are explored in it, and why it would be appropriate as a piece of art at the new Parramatta campus."
The Selected Compositions
Maxwell Mollica — Slow Blinking Street Light
This work is a double single containing the intro track "Slow Blinking Street Light" (0:00–1:18) and EDM break-core track "Breaking In Stereo" (1:18–4:37), both created under the artist name Maxwelliumn as part of my 4th year EP. This EP entitled "The City Sprawl" aimed to capture my experience growing up in Western Sydney as a rapidly evolving ecology of development and culture. These tracks delve into how the landscape of newly built high-rises and mass-built developments contrast with the familiar streets and infrastructure that I grew up with, and how even though the world around us changes, the people, characters, and culture stay as familiar as the roads we travel on.
"Breaking In Stereo" in particular delves into the omnipresent car cultures that thrive in Western Sydney, popping the hood on characters and stereotypes of Hoons and Revheads, attempting to capture their thoughts and motivations — whether that be attempting to satisfy some doubtful masculinity or just to feel in control of the powerful hum of a loud motor. In creating both tracks I heavily utilised the sounds of my environment, using audio of cars driving by at night, the ambience of Western Sydney streets, and my first car with its extremely loud exhaust — grounding the track to Western Sydney in its composition as well as concept.
Jessica Foreman — Lagoon Vignettes
With melodies inspired by the song of the Australian Currawong, this piece for piano and oboe captures the beauty and diversity of a lagoon and its surrounding bushland, nestled in Blue Mountains suburbia. The tranquil haven is frequented by locals at all hours of the day, and is an important part of the community. "Lagoon Vignettes" takes you on a journey through its surrounding mazes of shimmering blue reeds, a dark wilderness, a grove of wattle trees, and a vista opening out to the sparkling water.
The beautiful scenery is accompanied by a rich soundtrack of birdsong, and the particular melody of the local Currawongs forms the main theme of this piece (established by the oboe in the opening few bars). Like many other artists, my musical work is deeply inspired by the beauty of Australia's landscape, in particular my Blue Mountains home. A chromagram of "Lagoon Vignettes" would bring a little fragment of the Blue Mountains, a significant Australian landmark, onto the new Conservatorium Parramatta campus, representing the diverse homes our musicians come from, and the timelessness of capturing the world's beauty through art.
Professor Deborah Cheetham Fraillon — Long Night Chorale
A choral work that layers vocal harmonics into rich, sustained tonal fields. The piece explores the depth of human voice through overlapping pitches and resonant intervals that shift gradually over time.
To be updated...
Alexander Benson — Skyscrapers
'Skyscrapers' stands as both a musical and symbolic gesture toward the Conservatorium's expansion into Parramatta, articulating an ascent in artistic vision that parallels its architectural elevation. Composed and produced in the pursuit of recognition for the new campus, Skyscrapers contemplates height not merely as a measure of space, however as a metaphor for creative aspiration and freedom to express.
Infused with its distinctive architectural symbolism, this excerpt invites the listener to envision the conservatorium's musical expansion as an ever unfolding expressive continuum, ceaselessly constructed and an upward striving skyline of Sydney's artistic possibilities… Through its focus on height and an ever building sonic structure, 'Skyscrapers' parallels the institution's ambition to extend its artistic, educational, and community reach into Western Sydney, emerging as a major cultural presence.
As the Conservatorium's first major growth beyond its rich historic city campus, I am delightfully enthusiastic and blessed to be furthering my artistic development within such a vibrant and cohesive ecosystem of world class artists and educators. This is such an important step in strengthening and growing not only the University of Sydney's community, but strengthening the vibrant culture of the Conservatorium of Music students into these world class facilities, equipping us with industry standard experience and studio workspaces!
Wall Specifications
26m
Total Wall Width
530
Total Panels
4
Horizontal Bands
7
Panel Type Variations
Each panel is 100mm wide. The four bands have different heights (735mm–1,900mm) and different lengths (10m–16m), creating a non-uniform grid where shorter bands are centred within the total 26m wall width. Band 2 is the tallest at 1,900mm but the shortest at 10m, while Band 3 spans the full 16m as the longest band.
The Four Analysis Systems
Each system extracts a different dimension of acoustic information from the audio signal.
Pitch Analysis
Pitch analysis decomposes the audio signal into its fundamental chromatic content using a variant of the Constant-Q Transform. The audio spectrum is mapped onto the 12 pitch classes of the Western chromatic scale (C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯, B).
Technical Detail
At each cue point, an 8,192-sample FFT window is applied. Each frequency bin is mapped to its nearest MIDI note, and the corresponding pitch class accumulates the magnitude. The resulting 12-bin chromagram is normalised by peak energy and raised to a power curve (γ = 2.0) to enhance tonal contrast between dominant and subordinate pitches.
Visual Result
Panels in regions of strong harmonic content receive higher-energy pitch classes, producing warmer or brighter panel assignments. Quiet or atonal passages produce more uniform distributions.
Rhythm Analysis
Rhythm analysis examines the distribution of energy across logarithmically spaced frequency bands, capturing the spectral envelope of rhythmic and timbral content rather than pitched material.
Technical Detail
The frequency spectrum (20 Hz–Nyquist) is divided into 12 logarithmic bands. Energy in each band is accumulated and averaged. An alternation factor modulates odd/even bands based on total intensity, simulating the perception of rhythmic pulse. The result is normalised and contrast-enhanced with a γ = 2.0 power curve.
Visual Result
This mode responds strongly to percussion, transient attacks, and broadband noise events. Low-frequency-dominant passages (bass, kick drums) concentrate energy in the lower bins, whilst cymbals and high-frequency textures fill the upper bins.
Intensity Analysis
Intensity analysis measures the overall amplitude envelope at each cue point position, providing a direct representation of loudness variation across the timeline of the composition.
Technical Detail
A configurable analysis window (default 500ms) is centred on each cue point. The average absolute amplitude across all samples within the window is computed. All cue intensities within a band are then normalised using min–max scaling, producing values in the 0–1 range. An intensity multiplier parameter allows manual scaling of the amplitude mapping.
Visual Result
Each cue point receives a single amplitude value that determines which of the 7 panel types (shapes/colours) represents that cue's section. Quiet passages map to lower-numbered panel types (fewer subdivisions, darker colours), while louder passages map to higher-numbered types (more subdivisions, brighter colours).
Density Analysis
Density analysis evaluates the spectral centroid-weighted energy distribution, capturing how "thick" or "thin" the frequency content is at each moment — a measure of timbral complexity and spectral mass.
Technical Detail
Energy is computed as amplitude² for each FFT bin, then weighted by frequency (E × f) and accumulated into 12 logarithmic bands. This frequency-weighted energy metric emphasises bands where both energy and frequency are high, approximating the perceptual "brightness" or density of the sound. Results are normalised and shaped with a γ = 0.8 compression curve.
Visual Result
Dense, harmonically rich passages (full orchestra, distorted textures) produce high values across many bins, while sparse or monophonic passages concentrate energy in fewer bins. This creates a visualisation responsive to textural complexity.
Colour Mapping
The colour of each panel is determined by its assigned shape type through a configurable colour schema.
Colour Schema: Lava
The primary colour schema used for Station 60 is "Lava" — a thermal gradient mapping that assigns deep reds and blacks to lower-energy panel types, progressing through oranges and yellows to bright whites for the highest-energy panels. The HSL colour space is used with base hues ranging from 0° (red) through 20°, 35°, 45°, to 55° (yellow), with lightness modulated by the panel's position in the intensity spectrum.
Panel types 1–7 mapped across the Lava colour gradient (approximate representation)
Configurable Parameters
Luminosity
Controls the overall brightness multiplier applied to all generated colours.
Saturation
Adjusts colour vividness. Values above 100% add a colour boost multiplier for hyper-saturated output.
Intensity Range
Defines the min/max bounds of the colour gradient. Narrower ranges concentrate panel assignments toward similar colours.
Band Brightness
Per-band brightness adjustment, allowing each horizontal band to have independent luminance levels.
Colour Inversion
Reverses the colour assignment order, mapping high-energy panel types to dark colours and vice versa.
Custom Overrides
Individual panel types can have their colours manually overridden with specific hex values.
Shape Mapping
Each panel is assigned one of 7 shape types, determining its internal subdivision pattern.
The 7 Panel Types
The right-hand card shows the actual shape of each panel type — its physical geometry drawn as a thin black profile on the panel's fabrication colour.
Single Smooth Curved Arch
A single continuous panel surface — used for the quietest, most minimal passages.
Two Stepped Rectangles
The panel is divided into two equal vertical sections.
Three Small Semi-Circles
Three internal divisions creating a triplet rhythm within the panel.
Two Large Semi-Circles
Two broad divisions with larger curved profiles.
Three Triangular Sawtooth
Three angular divisions with a sawtooth wave profile.
Three Small Semi-Circles (high intensity)
Repeats the small semi-circular profile at higher intensity — three divisions in a brighter colour.
Three Triangular Sawtooth (maximum intensity)
Repeats the triangular sawtooth profile at maximum intensity — three angular divisions in the brightest colour.
Patch Cord Mapping System
The mapping from analysis data to panel type uses a "patch cord" metaphor borrowed from modular synthesis. The 12 chromagram bins (representing pitch classes, frequency bands, or intensity levels depending on the active analysis mode) are mapped through a configurable routing matrix to the seven available panel types.
Default Patch Configuration
Bins 0–2 → Shape 1 | Bins 3–4 → Shape 2 | Bins 5–6 → Shape 3 | Bins 7–8 → Shape 4 | Bin 9 → Shape 5 | Bin 10 → Shape 6 | Bin 11 → Shape 7
Bin Ordering Modes
Before mapping through the patch cord, chromagram bins can be reordered to change how analysis data is distributed across panels:
By Intensity
Bins sorted from highest to lowest energy — dominant features appear first in the panel sequence.
From C
Standard chromatic order starting from C.
From A
Chromatic order starting from A (concert pitch reference).
Circle of Fifths
Bins ordered by harmonic distance: C, G, D, A, E, B, F♯, C♯, G♯, D♯, A♯, F.
The Final Chromagram Image
How all elements combine into the final wall design blueprint.
The final chromagram image is a proportionally accurate representation of the 26-metre wall, rendered at high resolution (4,902 × 891 pixels at 3× scale). Each of the four bands is drawn at its true proportional height and width relative to the total wall dimensions, with each 100 mm-wide panel rendered as a coloured vertical column.
Rendering Pipeline
Cue Point Analysis
For each cue point in each band, the audio is analysed using an 8,192-sample FFT window. All four analysis modes (Pitch, Rhythm, Intensity, Density) are computed simultaneously and stored.
Panel-to-Cue Assignment
Each physical panel is mapped to its nearest cue point based on temporal position. The configurable "panels per cue" system allows non-uniform distribution — certain cue points can own more or fewer panels than others.
Bin Selection
Within each cue point's panel group, the position of each panel within the group determines which of the 12 chromagram bins it reads from. Bins are sorted by the active ordering mode.
Shape Assignment
The selected chromagram bin is routed through the patch cord matrix to determine the panel's shape type (1–7). This simultaneously determines the panel's colour through the active colour schema.
Composite Rendering
All 530 panels across all four bands are rendered into the final image. Each panel is drawn with its assigned colour, internal bar subdivisions matching its shape type, and black 2 px panel boundaries.
Architectural Features
The wall includes architectural elements that are represented in the chromagram: a door spanning Bands 1 and 2 at approximately the 66% mark, flanking wall panels, a poster display area within Band 2, and a wall opening. These non-panel regions are rendered as dark architectural elements in the visualisation, ensuring the final image accurately maps to the physical installation.
Software Interface
The Chromagram Station 60 application provides a real-time visual workspace for configuring and rendering the wall design.
The main canvas renders all 530 panels at proportional scale. Bands are drawn top-to-bottom (Band 4 → Band 1) with accurate height and width ratios. Each vertical strip represents one 100mm panel.
WAVEFORM ANALYSIS
Audio waveform with cue point markers (yellow lines). Each cue anchors a group of panels.
PANELS PER CUE
Adjustable panels-per-cue distribution. Each bar shows how many panels a cue point owns.
CONFIGURABLE PARAMETERS PER BAND
Cue Count
20
Distribution
Linear
Skew Factor
0.00
Cue Range
90%
Offset
1.00s
Analysis Window
500ms
Audio Compensation
0.0 dB
Intensity Multiplier
1.00×
Each chromagram bin (top row) is routed through a virtual patch cord to one of seven shape types (bottom). The vertical position of each connector determines the mapping. The colour swatch below shows the resulting panel colour for that shape assignment.
Data Output Examples
The software exports panel assignments as structured data for fabrication.
{
"timestamp": "2026-02-18T10:30:00.000Z",
"visualisationSettings": {
"numShapes": 7,
"colourSchema": "lava",
"lavaLuminosity": 1.0,
"lavaSaturation": 100,
"intensityRange": [0.3, 1.0],
"binOrdering": "intensity"
},
"shapeLegend": {
"1": { "colour": "#3d0a0a", "design": "Smooth Curved Arch" },
"2": { "colour": "#4a1a0e", "design": "Stepped Rectangular" },
"3": { "colour": "#8b1a1a", "design": "Small Semi-Circular" },
"4": { "colour": "#e06050", "design": "Large Semi-Circular" },
"5": { "colour": "#f0a090", "design": "Triangular Sawtooth" },
"6": { "colour": "#c89860", "design": "Small Semi-Circular (high)" },
"7": { "colour": "#f08070", "design": "Triangular Sawtooth (max)" }
},
"bandConfigs": [
{
"band": 4,
"fileName": "C04_SlowBlinkingStreetlight-MaxwellMollica.mp3",
"numCuePoints": 20,
"analysisMode": "pitch",
"panelShapeValues": [1,1,1,2,2,3,3,4,4,5,6,7,5,4, ...]
},
{
"band": 3,
"fileName": "C03_LongNightChorale-DeborahCheetham.mp3",
"numCuePoints": 23,
"analysisMode": "pitch",
"panelShapeValues": [2,3,4,5,6,6,5,4,3,2,1,1,2,3, ...]
},
...
]
}Station 60 Panel Layout
Generated: 2026-02-18
PANEL SHAPES
Band 4:
File: C04_SlowBlinkingStreetlight-MaxwellMollica.mp3
Length: 14m | Panels: 140 | Panel Width: 0.100m
1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 7, 5, 4, 3, 2, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 7, 5, 4, 3, 2, 1, 1, 2, 3, 4, 5, 6, 7, 6, 5, 4, 3, 2, 1, 1, 2, 3, 4, ...
Band 3:
File: C03_LongNightChorale-DeborahCheetham.mp3
Length: 16m | Panels: 160 | Panel Width: 0.100m
2, 3, 4, 5, 6, 6, 5, 4, 3, 2, 1, 1, 2, 3, 4, 5, 6, 7, 7, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6, ...
The PDF export provides a fabrication-ready document with colour legend, panel dimensions, and the complete comma-separated list of shape type numbers for each band.
For each cue point, the software computes four 12-bin arrays simultaneously. Below is an example of the analysis output for a single cue point:
PITCH CHROMAGRAM — Cue #8 @ 42.3s
C
0.92
C♯
0.15
D
0.67
D♯
0.08
E
0.45
F
0.31
F♯
0.12
G
0.78
G♯
0.21
A
0.55
A♯
0.04
B
0.38
Dominant: C (0.92), G (0.78), D (0.67)
RHYTHM SPECTRUM — Cue #8 @ 42.3s
0.85
0.72
0.58
0.45
0.34
0.28
0.22
0.18
0.15
0.12
0.08
0.05
Energy concentrated in low-frequency bands (bass-dominant)
INTENSITY — Cue #8 @ 42.3s
Normalised amplitude: 0.68 → maps to Panel Type 5 (Triangular Sawtooth)
DENSITY — Cue #8 @ 42.3s
0.05
0.12
0.25
0.42
0.65
0.88
0.95
0.82
0.55
0.30
0.15
0.08
Spectral centroid in mid-high frequencies — dense harmonic content
About the Chromagram Station 60 Application
The Chromagram Station 60 application was developed by Dr Ivan Zavada, Senior Lecturer in Composition and Music Technology at the Sydney Conservatorium of Music. This bespoke software tool translates the acoustic content of the four compositions into a precise, data-driven blueprint for the 530-panel wall installation at the new Conservatorium Parramatta campus. The software was developed in collaboration with Design Inc, Sydney Office — Australia-wide architecture and design practice. A special thank you to the entire team for the inspiration and vision of the facade design project. Thank you also to colleagues Jade O'Regan, Fiona Hill, and Benjamin Carey for organising the call for works and their contribution to the Design User Group.
Chromagram Station 60 — Sound Analysis Software for Architectural Panel Design
Four commissioned compositions · Four analysis systems · 530 panels · One wall