• A. Surface Reflectors and Portals
• B. Surface Reflectors and Reverb
• C. Diffraction
• D. Transmission
• E. Room-Aware Surface Reflectors (Optimization)

Note:

This page assumes you have already completed the Preparation for the Spatial Audio Tutorials as well as both Surface Reflectors Tutorial and Rooms and Portals Tutorial.

A. Surface Reflectors and Portals

Just like portals will open up a room area to let the sound propagate through it, it will also do the same through a reflective surface. At the end of the Surface Reflectors Tutorial, we noticed that reflections were occuring on openings of our mesh if we used simple cubes as surface reflectors. To fix this problem, Spatial Audio Portals are also aware of reflection paths and let them pass through. Reflection paths will even diffract on the borders of a portal.

1. Setup is simple, just placing a portal through a room and a surface reflector should do the trick.
   

   Reflection paths going through a Portal in the Game Object 3D Viewer

B. Surface Reflectors and Reverb

In a Room with late reverb, it is possible to feed early reflections into the reverb to make it more geometry aware.

1. In the Wwise project, open the Auxiliary Bus with the Reflect Effect applied to it.
   1. In the General Settings tab, make sure Use game-defined auxiliary sends is checked.
      

      Auxiliary Bus Property Editor General Settings tab to send early reflection to the room reverb
2. Play the scene and press the button in the small Room. With the player in the small Room, here is the Voices Graph we see:
   

   Early reflections in the small room are sent to the small room's reverb in the Voices Graph

C. Diffraction

When an object appears between the emitter and the listener, Spatial Audio can create diffraction paths that will go around the object. Depending on the angle of the path around an edge, the sound will be attenuated to simulate obstruction. You can enable diffraction per Sound and per Surface Reflector. An emitter emitting diffraction enabled sound will only diffract off a diffraction enabled reflective surface.

1. Enabling diffraction on the Sound:
   1. In the Positioning tab, make sure the Enable Diffraction checkbox is checked.
      

      Enable Diffraction on the Sound
2. Enabling diffraction on an AkSurfaceReflector component:
   1. Check Enable Diffraction. This will generate diffraction edges on the geometry sent to Wwise Spatial Audio. The diffraction edges will be visible in the game object viewer when Wwise is connected to the game.
   2. You may also want to check Enable Diffraction On Boundary Edges. This checkbox appears when the previous checkbox is checked. Boundary edges are edges that are connected to only one triangle. For example, edges around the Unity Quad 3D Object would be considered boundary edges.
      

      Diffraction enabled AkSurfaceReflector
3. In the Wwise Unity Demo Scene, the outside emitter, the barrier and the exterior of the building are diffraction enabled. Diffraction paths are in purple. Each one of them will create a virtual source placed where the sound will be heard from.
   

   Diffraction paths in the Game Object 3D Viewer

D. Transmission

When an object appears between the emitter and the listener, the sound can also pass through the object. Spatial Audio models this phenomena by applying occlusion filtering on the direct path of the sound. Occlusion values ranging from 0 to 1 can be applied on an AkSurfaceReflector or AkRoom components. The occlusion value is then sent to Wwise where the associated filter is applied according to the occlusion curves of the project. Typically, a value of 1.0 represents full occlusion, and a value of 0.0 indicates that sound can be transmitted through the geometry.

1. Enable transmission in the spatial audio init settings
   

   Spatial Audio Init Settings
2. The transmission value of a sound is the maximum occlusion value of AkSurfaceReflector or AkRoom components that the sound encounters in a direct path from the emitter to the listener.
   1. On AkSurfaceReflector components, associate an occlusion value for each submesh of the surface reflector mesh by populating the Occlusion Values array.
      

      Occlusion Values array on the AkSurfaceReflector component
   2. On AkRoom components, change the occlusion value in the Wall Occlusion parameter.
      

      Wall Occlusion parameter on the AkRoom component
3. Adjust the occlusion curves in Wwise Authoring in the Obstruction/Occlusion tab of the Project Settings.
   

   Occlusion curves in the Wwise Project Settings

E. Room-Aware Surface Reflectors (Optimization)

Each surface reflector added to Spatial Audio is analysed for diffraction edges and visibility. To optimize this step, each room can have a group of connected surface reflectors. Surface Reflectors associated with a room are not visible from other rooms. A Surface Reflector should be associated to a room if it is completely encompassed by it and if that room doesn't share surface reflectors with other rooms. Associating a room to a surface reflector is totally optional. If no room is selected, the surface reflector is added to a global group of surface reflectors. Associating surface reflectors to rooms will reduce the search space for ray casting performed by reflection and diffraction calculations.

1. Choose a Room under Associated Room in the AkSurfaceReflector component to associate them.
   

   Room-Aware AkSurfaceReflector