The decision guide

Everything in this book converges here. You have a project; the field has a dozen tools; the promise of a field guide is that these two facts meet in minutes, not weeks. This chapter delivers the promise twice: first as questions, then as worked scenarios.

The four questions

Nearly every spatial audio decision resolves from four axes:

1. What's the deliverable — a scene, feeds, or a platform master? If the venue varies or the listener steers: scene (Ambisonics). If one known rig defines the piece: channel feeds. If a commercial platform names the spec: that platform's paradigm, full stop (Chapter 22).

2. Who's listening, on what? One tracked head (VR/binaural), many untracked heads on headphones (Chapter 13's caveats), one sweet seat (XTC territory), or a room of wanderers (arrays; order and decoder choices per Chapters 7 and 12)?

3. Is the material discrete, diffuse, or both? A few precise foreground sources lean object-wise (panbin~, engine objects, Atmos objects). Fields, rooms, and weather lean scene-wise. "Both" is the professional's default answer, and the bed + foreground split (Chapters 9, 21, 22) is the standing solution.

4. What are the budgets? Channel count and CPU (order economics, Chapter 7), latency (room~'s 53 ms, xtc~'s 512 samples), licensing (open bus vs. platform), and the scarcest one — setup time in the venue (Chapter 5's monitor-binaurally-decode-on-site discipline).

Answer four questions, and the scenarios below mostly write themselves.

Worked scenarios

Live electronics set (club/venue, rig varies per gig). Compose order-3 in Max; master bus per Chapter 15; monitor binaurally in rehearsal. Per venue: decode~ to the house layout — allrad, max_re 1 for whatever gappy array exists (Ch. 12) — with Chapter 5's tape-measure hour. Keep a stereo decode on a fader as the soundcheck insurance policy. Why not objects/Atmos: no renderer at the club; the scene decodes anywhere.

Gallery installation, speaker dome, three months unattended. Author in Max with the widgets; exhibit per Chapter 18: Pd headless on a small computer, same objects, decoded to the dome; order 3–4 if the dome is dense (Ch. 7's wandering-audience case for higher order). LFE/subs via W-derived send (Ch. 17). The trap to avoid: composing on the dome. Compose binaurally, calibrate on site.

VR title / 360 video. Foreground as engine objects; world as ambisonic beds authored on your Max production line and delivered as AmbiX WAV (order 1–3 per platform); HMD rotation does the head tracking (Ch. 21). For plain 360 video: order-1 AmbiX + head-locked stereo, injected metadata (Ch. 20). Why not pure scene: foreground sharpness; why not pure objects: the world would cost per-raindrop.

Binaural fiction / podcast drama (headphones, no tracking). Order-3 scene; magls; room per scene from Chapter 11 (the externalization stack); featured close voices via panbin~ (Ch. 9's fork); print per Chapter 20. Favor motion and staging that survive front/back ambiguity (Ch. 13). Why not Atmos: Dolby's binaural is a platform render; here you are the renderer and can voice it.

Commercial music release "in Atmos." The spec answers question 1: author beds + objects against Dolby's renderer (Ch. 22). Your kit still earns its keep upstream — spatial sketching, ambience design decoded into the bed, bed2hoa~ for monitoring object stems binaurally without renderer seats. Keep stems + trajectories as the archival truth; print Atmos and scene masters as siblings.

Field recording / documentary sound. First-order mic per Chapter 19 (craft section verbatim); deliver scene masters + binaural prints; vmic~ to derive spot mics in post; hybrid with encoded foreground when the story needs focus (Ch. 7's recorded-bed pattern).

Concert hall / acousmatic diffusion. The historical home turf. Scene-based composition; venue decodes (often the festival provides one — ship AmbiX + README per Ch. 8 and you are the easiest guest they've had); rehearse spatial gestures with rotate~/directional~ automation rather than fader-diffusion alone. Order 3 travels; order 5 if the hall's rig genuinely resolves it.

A client demo next Tuesday. Chapter 3's patch, your material, twenty minutes, headphones across the desk. Nothing in professional audio demos better per unit effort — which is, after all, how this book got you here.

When the answer is "not Ambisonics"

The guide is only trustworthy if this list is real. Reach elsewhere when: the deliverable is a named platform spec (author in that ecosystem); it's stereo/mono content with stereo ambitions (a great stereo mix beats a reluctant spatial one); the piece is a few point sources, headphones-only, no future on speakers (direct binaural per source — even then your panbin~ does it in-family); the rig is wildly irregular and the material channel-conceived (a 40-speaker sculpture where each speaker is a voice is channel-based art — compose it as channels); or latency is king (sub-5 ms monitoring paths shouldn't detour through convolution renderers).

The last checkpoint

Four questions — deliverable, listener, material, budgets — then the scenario table; and the honest "elsewhere" list keeps the whole guide credible. You came to this book not knowing what Ambisonics was. You leave with a bus in your patch cords, instruments on it, renders out of it, and — the actual goal — judgment about when it's the right tool. The appendices hold the reference tables and the road onward. Go make something three-dimensional.