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Sound Classes & Submixes

The bus/category routing system. Classes group sources; Submixes are the output endpoints.

SoundClass

A USoundClass is a category (Music, SFX, Dialogue, UI). Sources reference their class; properties propagate down a class hierarchy.

Property Effect
Volume Per-class master volume
Pitch Per-class pitch scalar
Parent Class Inherit settings
Stereo Bleed Cross-channel bleed for stereo sources
LFE Bleed Low-frequency channel mix
Low Pass Filter Frequency Per-class LPF

SoundMix

A snapshot of (SoundClass → Volume/Pitch/LPF) overrides. Push at runtime to duck music during dialogue:

UGameplayStatics::PushSoundMixModifier(World, DialogueMix);
// later
UGameplayStatics::PopSoundMixModifier(World, DialogueMix);

Submix

USoundSubmix is the audio output bus. Sources go through a chain of submixes (e.g. SFX_Submix → Master_Submix). Submixes can have submix effects:

  • Compressor
  • EQ
  • Convolution Reverb
  • Multiband Compressor
  • Submix Delay
  • Custom MetaSound submix patch

Routing example

Footstep Sound → SFX_Class → SFX_Submix → Master_Submix → Output
Music_Stream → Music_Class → Music_Submix (Compressor) → Master_Submix

Console commands

au.SubmixUtilityDisplayInfo 1     # show submix graph
au.LogPlayingSounds 1              # log every voice
au.3dVisualize.Enabled 1           # visualize attenuation cones

See also