MetaSounds

Select the audio layer first

Read references/system-selector.md.

• One playable procedural/parameterized sound -> MetaSound Source.
• Reusable graph behavior inside other MetaSounds -> Patch.
• Same graph with different default inputs -> Preset.
• Cross-category volume/filter/pitch control -> Audio Modulation/Control Buses.
• Sample-accurate musical scheduling -> Quartz plus MetaSound where needed.
• Fixed simple one-shot -> Sound Wave or simple source may be enough.

Keep gameplay authority outside the audio graph. MetaSound consumes events and parameters to render feedback; it does not decide whether a hit, purchase, cooldown, or state transition is valid.

Execute

1. Define the sound's informational job, duration, spatial context, variation, and mix priority.
2. Choose Source, Patch, Preset, or a simpler asset and define the public input/output interface.
3. Build a minimum audible signal path and correct one-shot or indefinite lifetime.
4. Add deterministic/random variation, envelopes, filters, synthesis, or layering in bounded stages.
5. Drive runtime changes through MetaSound Inputs/Triggers on the playing Audio Component.
6. Configure attenuation, spatialization, concurrency, sound class/submix, and modulation routing.
7. Test repeated triggering, virtualization/lifecycle, listener distance, and worst-case voice counts.
8. Profile audio/render-thread cost and the complete mix during representative gameplay.

Load only what applies:

• references/assets-and-graph-contract.md
• references/runtime-parameters-and-events.md
• references/variation-and-recipes.md
• references/spatialization-lifetime-and-concurrency.md
• references/modulation-mixing-and-quartz.md
• references/presets-patches-and-interfaces.md
• references/builder-api-and-output-watch.md
• references/debugging-and-performance.md

Hard rules

• Only a MetaSound Source is directly playable; Patches encapsulate reusable graph behavior.
• Use Presets for inherited graphs with overridden default Inputs; do not duplicate the graph.
• Use Inputs for values that change during playback. MetaSound Variables are graph-internal, cannot be accessed from Blueprint, and do not register external playback-time changes.
• Set runtime parameters on the Audio Component before Play when the first audio block depends on them.
• Keep UE.Source.OneShot and its On Finished contract for finite sounds; remove it from indefinite sounds.
• Remove DC, avoid discontinuous waveform jumps, and bound gain before output.
• Define concurrency and cleanup for every repeatedly triggered or looping source.
• Use Audio Modulation for shared mix state; do not update every MetaSound instance each frame.
• Critical gameplay information must have a non-audio equivalent and survive mix/accessibility settings.
• Profile at realistic simultaneous voice counts; graph complexity alone is not the final cost.

See references/sources.md for the UE 5.8 source trail.