Listener Actor¶

AAbolethListenerActor is a ready-made actor that provides zero-configuration speech-to-text when placed in a level. It wraps the full STT pipeline --- microphone capture, VAD, and transcription --- so you can start receiving speech events without writing any setup code.

Quick Start¶

Drag AbolethListenerActor from the Content Browser into your level.
Press Play.
The actor auto-activates, loads the STT system, and begins listening.

All transcription events are exposed as BlueprintAssignable delegates directly on the actor.

Configuration Properties¶

Override these in the Details panel to customize behavior per-instance.

Property	Type	Default	Description
`bAutoActivate`	`bool`	`true`	Automatically activate and begin listening on `BeginPlay`.
`bOverrideVADThreshold`	`bool`	`false`	When `true`, use `VADThresholdOverride` instead of the project-wide setting.
`VADThresholdOverride`	`float`	`0.5`	Per-instance VAD speech probability threshold (0.0--1.0). Only applied when `bOverrideVADThreshold` is `true`.
`bOverrideAudioDevice`	`bool`	`false`	When `true`, use `AudioDeviceIndexOverride` instead of the system default.
`AudioDeviceIndexOverride`	`int32`	`-1`	Index of the audio input device to use. `-1` uses the system default. Only applied when `bOverrideAudioDevice` is `true`.
`bOverrideCaptureMode`	`bool`	`false`	When `true`, use `CaptureModeOverride` instead of the project-wide setting.
`CaptureModeOverride`	`EAbolethCaptureMode`	`VADAutomatic`	Capture mode for this instance. Only applied when `bOverrideCaptureMode` is `true`.

Functions¶

Function	Specifier	Return	Description
`Activate`	BlueprintCallable	`bool`	Loads the STT system (if needed), opens the mic, and begins listening. Returns `true` on success.
`Deactivate`	BlueprintCallable	`void`	Stops listening and releases the microphone. Does not unload the model.
`IsActive`	BlueprintPure	`bool`	Returns `true` if the actor is currently listening.
`GetMicComponent`	BlueprintPure	`UMicCaptureComponent*`	Returns the internal microphone capture component.
`StartManualCapture`	BlueprintCallable	`void`	Begin push-to-talk recording. Only valid when capture mode is `PushToTalk`.
`StopManualCapture`	BlueprintCallable	`void`	End push-to-talk recording and submit audio for transcription.
`IsManualCaptureActive`	BlueprintPure	`bool`	Returns `true` if a manual capture session is in progress.
`SetCaptureMode`	BlueprintCallable	`void`	Switch between `VADAutomatic` and `PushToTalk` at runtime.
`GetCaptureMode`	BlueprintPure	`EAbolethCaptureMode`	Returns the active capture mode.

Events¶

All events are exposed as BlueprintAssignable delegates. Bind them in the Details panel or via AddDynamic in C++.

The Listener Actor exposes the same event set as the subsystem. See Events & Delegates for the full delegate reference including parameter signatures.

Usage Examples¶

BlueprintC++

Place an AbolethListenerActor in the level.
Select it and open the Details panel.
Scroll to the Events section.
Click + next to OnUtteranceProcessed and bind it to your handler.
The actor auto-activates on play --- no further setup required.

// In your level setup or game mode
AAbolethListenerActor* Listener = GetWorld()->SpawnActor<AAbolethListenerActor>();

Listener->OnUtteranceProcessed.AddDynamic(this, &AMyGameMode::HandleSpeech);
Listener->OnSpeechDetected.AddDynamic(this, &AMyGameMode::HandleSpeechStart);
Listener->OnSilenceDetected.AddDynamic(this, &AMyGameMode::HandleSilence);

// Auto-activates by default, or call manually:
Listener->Activate();

Notes¶

One listener at a time. Only one Listener Actor (or Listener Component) should be active per game instance. The underlying subsystem is a singleton.
GetSTTSubsystem() is C++ only. For Blueprint access to the subsystem, use the engine Get Subsystem node.
Deactivating the actor stops capture but leaves the Whisper model loaded. Call UnloadSTTSystem on the subsystem to fully release resources.