Composing in Ambisonics

Ambisonics gives composers access to a three-dimensional sound field as primary compositional material — not as an effect added after the fact, but as a structural dimension on the same level as pitch, rhythm, and timbre. Movement, depth, envelopment, elevation, point-source vs. diffuse: all of these can be composed, scored, and rendered with the ICST toolset.

This section collects frameworks and references for thinking and working spatially as a composer — from analytical listening to studio practice.

Chapter 1 — Listening Analytically

Before composing spatial trajectories, it helps to hear them clearly in other people’s work. This chapter introduces a practical listening framework used in the ICST ascolta sessions: Smalley’s three spatial categories, five analytical questions, and three exercises for active spatial listening.

→ Ascolta Listening Guide — Analytical Spatial Listening

Chapter 2 — 10 Questions When Composing in 3D Space with Ambisonics

1. Ontology of the Piece — What Is There?

Key question: What kind of “world” does the piece construct in space?

Sub-questions: Am I working with recognisable places/scenes (city, landscape, interior) or with abstract spatial formations? Are there identifiable “agents” (sound objects) and “environments” (fields, textures)?

Decision options:

  • realistic / ecological
  • abstracted from real spaces
  • purely abstract / “imaginary space”
  • focus on individual objects
  • focus on textures/fields

2. Role of Space — Space vs. Spectrum/Time

Key question: What primarily carries the form — spatial gestures or spectral‑temporal development?

Sub-questions: Could the piece still work in stereo, or would the form collapse? Are there sections defined almost entirely through spatial change (space‑form)?

Decision options:

  • form primarily spectral/temporal, space secondary
  • form equally space + spectrum/time
  • form primarily spatial (spatial architecture, sounds fill it)
  • mark per section: “S > Sp/T”, “S = Sp/T” or “S < Sp/T”

3. Spatial Layers

Key question: How many distinguishable spatial layers are there?

Sub-questions: Which zones matter (front, back, above, below, near, far)? Is there a constant “backdrop” against which foreground gestures play out?

Decision options:

  • foreground objects (clearly localisable)
  • midfield texture
  • background ambience / far field
  • overhead layer / “ceiling”
  • floor / below ear level

For each layer, briefly note: sound type, density, typical movements.

4. Object Count and Density

Key question: How full is the space at any given moment?

Sub-questions: How many active objects can be consciously tracked simultaneously? Are there deliberate density tipping points (gesture → texture, clarity → cloud)?

Decision options:

  • max. number of “trackable” objects: ___
  • typical density per section (e.g. 1–3 / 4–8 / >8 objects)
  • mark moments where you intentionally move into “excess” or “emptiness”

5. Trajectories and Gesture Types

Key question: What kinds of movement appear?

Sub-questions: Do I use geometric movements (circles, rings, spirals) or gestural ones (approach, flight, circling)? Are there “signature gestures” that recur?

Decision options:

  • circle / orbital movement
  • line / travel in one direction
  • vertical movement (bottom–top / top–bottom)
  • explosion / implosion
  • swarm / flock (many similar trajectories)

For each gesture, briefly note its purpose (e.g. “opens new section”, “climax marker”).

6. Localisation vs. Diffuseness

Key question: When should sounds be pinpoint, when spread?

Sub-questions: Are there dramaturgically important moments of maximum sharpness or maximum envelopment? Do I use focus/defocus transitions deliberately as a formal element?

Decision options — scale 1–5 per section:

  • 1 = very diffuse / cloud
  • 3 = mixed
  • 5 = very precise localisation

Mark moments: focus gesture (diffuse → point source) / defocus gesture (point source → diffuse).

7. Target Listening Scenario

Key question: For which real playback setting am I composing?

Sub-questions: Which loudspeaker configuration do I have in mind (dome, 5.1/7.1, headphones)? Must the piece work across multiple formats?

Decision options — primary target:

  • 3D dome / specific array
  • multichannel (5.1 / 7.1 / 22.2)
  • binaural (headphones)

Secondary: stereo compatibility important / unimportant. Note constraints per target (e.g. “overhead structures attenuated binaurally”).

→ Listen: #13 Listening Twice — stereo vs. immersive · #14 5.1 surround vs. Ambisonics UHJ · #15 UHJ recordings from the 1970s

8. Audience and Listening Experience

Key question: How spatially “trained” is the assumed audience?

Sub-questions: Is the piece more likely performed at festivals with experienced audiences or in general audience contexts? Must contrasts be clear and legible, or may they remain subtle?

Decision options:

  • spatially experienced audience
  • mixed
  • limited experience

Consequence: strong, clear spatial contrasts / fine, microscopic differences / combination (e.g. clear macro arc + subtle details).

→ Listen: All ASCOLTA sessions — a range of audiences from specialists to first-time listeners

9. Real-Space Reference and Archetypes

Key question: How do I relate to real spaces / spatial metaphors?

Sub-questions: Do I use familiar archetypes (tunnel, plaza, interior, exterior, height, abyss)? Do I want to reproduce real spaces, defamiliarise them, or construct something physically impossible?

Decision options:

  • mimesis (reproduction of real spaces)
  • defamiliarisation / exaggeration
  • “impossible” spaces

List the archetypes used and their musical function (e.g. “tunnel = transition”, “plaza = culmination point”).

→ Listen: #10 Natasha Barrett — spatial argument about containment and release

10. Work Identity and Documentation

Key question: What actually constitutes the “work” — and how do I document it?

Sub-questions: Is the HOA master file the actual core of the work, or a specific decoder configuration? Does it need a score, patch, text instructions, layout plans to remain reconstructible?

Decision options — reference:

  • HOA master (e.g. 7th order)
  • specific loudspeaker version (e.g. 24.1 layout X)
  • binaural release

Documentation:

  • loudspeaker plan(s)
  • written description of spatial form(s)
  • screenshots/exports of trajectories / automation
  • custom “spatial score” (diagrams/timeline)

Chapter 3 — Spatial Counterpoint in Ambisonics

1. Introduction: From Stereo to Ambisonics

  • Problem: limited spatial differentiation in stereo/5.1 and its consequences for polyphony.
  • Ambisonics as a “space-agnostic” format that conceives voices as sound fields (B‑format/HOA).
  • Goal: Spatial Counterpoint as the organisation of multiple Ambisonics voices in spherical space.

2. Ambisonics Fundamentals for Spatial Counterpoint

  • Brief overview: order, spherical harmonics, decoding, sweet-spot problem.
  • Ambisonics “voice”: source, stream, or field (e.g. dedicated HOA buses, object groups).
  • Differences from loudspeaker layouts (e.g. Brant-style): flexibility vs. absent visual anchoring.

3. Perception in the Ambisonics Listening Space

  • Localisation, precision, and front-bias in a typical Ambisonics setup.
  • Influence of order, loudspeaker density, and room acoustics on the audibility of spatial polyphony.
  • Binaural headphone vs. loudspeaker Ambisonics: differences for spatial counterpoint.

4. Models of Spatial Polyphony in Ambisonics

  • Trajectory voices: individual sources/objects as moving voices in the Ambisonics field.
  • Layer voices: different HOA buses or zones (e.g. near-field/far-field, above/below).
  • Field voices: diffuse vs. directed fields, clusters/clouds, noise layers as polyphonic units.

5. Historical and Current Ambisonics Practice

  • Early multichannel/spatial music as precursors, transition to HOA practice.
  • Examples: studio productions and concert settings using Ambisonics for polyphonic spatial design.
  • Role of Ambisonics institutes/studios in developing spatial counterpoint models.

6. Parameters of Spatial Counterpoint in the Ambisonics Context

  • Spherical parameters: azimuth, elevation, distance (synthetic), spread, order.
  • Coupling with spectrum, dynamics, and density in Ambisonics buses.
  • Technical parameters: order limitation, energy vs. velocity decoding, subwoofer management.

7. Types of Spatial Counterpoint Formation in Ambisonics

  • Canon in spherical space: temporal and spatial displacement of motifs (e.g. rotating around the listening position).
  • Layer counterpoint: different orders/buses (e.g. N=1 vs. N=3) or differing diffuseness as contrapuntal strata.
  • “False HOA polyphony”: apparent polyphony through rapid movement or dynamic order/diffuseness of a single source.

8. Notation and Representation for Ambisonics Composition

  • Spherical notation forms (polar-coordinate diagrams, 2D projections, layer graphics).
  • Software-based score: DAW automation, Ambisonics panner curves, OSC scenarios as structural notation.
  • Analysis diagrams: snapshots of energy density on the sphere, time–space sketches.

9. Compositional Strategies and Guidelines in Ambisonics

  • Heuristics for HOA polyphony: maximum voice count, minimum angular and temporal distances, order per voice.
  • Handling masking: spectral and spatial separation of voices, use of height and diffuseness as voice parameters.
  • Practical don’ts: overfull N=3 fields, unmotivated rotations that destroy polyphonic clarity.

10. Analysis Examples of Ambisonics Works

  • Selection of 2–3 HOA works (or own pieces) as case studies.
  • Mapping specific passages to the models in section 4 and the types in section 7.
  • Discussion: which constellations work in the Ambisonics listening space, which break down?

11. Outlook: Spatial Counterpoint in Ambisonics Ecosystems

  • Integration into Ambisonics pedagogy: from B‑format basics to complex spatial counterpoint exercises.
  • Transferability to Atmos, WFS, XR (Ambisonics as compositional “neutral layer”).
  • Perspectives: tools for automated analysis of spatial counterpoint in Ambisonics productions.

Chapter 4 — Spatial Parameters as Compositional Material

Coming soon. How to work with azimuth, elevation, distance, and diffusion as scoreable parameters — notation approaches, REAPER automation, and OSC control from live performance setups.

Chapter 5 — Studio Practice at the ICST

Coming soon. Compositional workflows developed from residencies at the ICST Kompositionsstudio — session templates, B-Format archiving, and multi-format delivery (speaker, binaural, UHJ).

References

Books

Key Papers

Michael Gerzon

Video