Spatial Audio Objects

AkAcousticTexture

Unreal object representing a Wwise Acoustic Texture. Can be created either by drag-and-drop from the Wwise Picker or by right-clicking in the Unreal Content Browser. Once created, it can be applied on a AkSurfaceReflectorSetComponent's polygons or on a AkSpotReflector.

• Properties
  • Edit Color: Editor-only property defining the color to be used when colorizing AkSurfaceReflectorSetComponent polygons that have an AkAcousticTexture assigned.

AkSpotReflector

The Spot Reflector actor is an experimental feature. It allows to place an omnidirectional point reflector in the 3D world. Spot reflectors make sense when they are placed on far away objects that have a large radius; like a distant mountain.

Spot Reflectors will reflect any sound coming from an AkComponent that has Enable Spot Reflectors enabled and that is positioned in the same area. An AkComponent will feed to spot reflectors if they both are outside rooms. If the AkComponent is in a room, it will only feed to spot reflectors inside the same room. Rooms can be created with a volume that has an AkRoomComponent attached.

Calls AK::SpatialAudio::AddImageSource() from the Spatial Audio API on BeginPlay.

• Properties:
  • Aux Bus: AkAuxBus that has the AkReflect plug-in for early reflection DSP. This aux bus should enable game-defined auxiliary sends with enable positioning set to 2D.
  • Acoustic Texture: AkAcousticTexture used to filter sounds reflected by this image source.
  • Distance Scaling Factor: Image source distance scaling. This number effectively scales the sourcePosition vector with respect to the listener and, consequently, scales distance and preserves orientation.
  • Level: Game-controlled linear level for this source.

AkSurfaceReflectorSetComponent

Representation of a Geometry Set in Unreal Engine 4. This component needs to be attached on a AVolume actor. On BeginPlay, all of the volume's enabled polygons will be sent to the SpatialAudio engine.

• Properties
  • Enable Surface Reflector Set: Enables or disables this component
  • Acoustic Surfaces: Array defining the AkAcousticTexture associated with each polygon. The index in the array is represented in the Game Viewport when the parent volume is selected. Once a texture is assigned to a polygon, the polygon is colorized using the texture's Edit Color, and the Acoustic Texture's name is printed on the polygon in the Game Viewport. Assigning None as an acoustic texture will make the surface completely reflectible, no additional texture filter will be applied. Each polygon can also be enabled or disabled with the Enable Surface checkbox.

AkRoomComponent

This component can be added to any volume, and then creates a Spatial Audio Room. Rooms have two purposes:

• Allow for oriented reverb. All auxiliary buses applied on a game object within a room will be oriented towards the volume's front vector.
• Used in conjunction with AkAcousticPortal, allows routing the wet signal from one room through a portal, to another room.

In both cases, the auxiliary bus used should have its positioning options set to 3D, with positioning enabled, and have an attenuation assigned.

• Properties
  • Enable Room: Enables or disables this component
  • Priority: The precedence in which the rooms will be applied. In the case of overlapping rooms, the one with the highest priority is chosen. If two or more overlapping rooms have the same priority, the chosen room is unpredictable.
  • Wall Occlusion: Used to set the Wwise occlusion value on emitters in the Room, when no audio paths to the listener are found via sound propagation in Wwise Spatial Audio. This value can be thought of as 'thickness', because it relates to how much sound energy is transmitted through the wall. The valid range is 0.0f-1.0f, and is mapped to the occlusion curve as defined in the Wwise project.

AkSpatialAudioVolume

For your convenience, an AkSpatialAudio volume is included in the integration. It consists of a simple volume with a AkSurfaceReflectorSetComponent, a AkRoomComponent and a AkLateReverbComponent attached.

AkAcousticPortal

Representation of a Portal in Unreal Engine 4. Allows for sounds contained in a volume with AkRoomComponent attached to leak into other volumes with AkRoomComponent attached. Such volumes overlapping with Portals are detected at initialization time. Both 2D and 3D sounds can be routed through a portal.

• Properties
  • Initial state: Whether this Portal should be initialized in an open (enabled) or closed (disabled) state.
  • Obstruction Refresh Interval: Time interval between occlusion/obstruction checks. Set to 0 to disable occlusion on this component.
  • Obstruction Collision Channel: The object collision channel used for creating the collision of the obstruction ray-casts (between the Portal and the listener) with the desired geometry.