You can apply positioning to Audio and Auxiliary Busses as easily as applying it to objects. All you have to do is load the bus into the Property Editor and apply the Speaker Panning or 3D Spatialization as you would to a sound object. For more information on this process, refer to Working with Speaker Panning and Working with 3D Spatialized Objects.
Because both busses and sound objects can be positioned, audio designers are empowered with greater control over sound propagation. While the added complexity is not always needed, positioning busses can be very useful for added realism in certain scenarios, such as the following:
Virtual Surveillance or Loud-Speaker System: A system in your game allows players to snoop on other players with a hidden microphone. The audio is captured and retransmitted on the other end of the map from a virtual loudspeaker. After applying a lo-fi effect, the submix is spatialized to sound as if it is emitting from the loudspeaker.
Acoustic Portals: You are making a virtual reality game with a heavy emphasis on spatial audio. It is of utmost importance to simulate acoustic phenomena realistically and convincingly to maintain the illusion. You would like the listener to be able to hear the reverberated sound coming from an adjacent room. All sounds in the room will be mixed together, fed into a reverb unit, and then the output of the effect will be spatialized and positioned as if it were coming through a doorway.
Early Reflections and Other Effects: Sometimes applying an Effect per voice is too cumbersome, but applying it as a send Effect on a shared bus is too broad to be useful. Really, you would like to create an instance of a bus for each sound emitter on which you can apply your Effect. Spatialization may take place downstream of the submix, or perhaps your plug-in takes care of it. This is the strategy that Reflect uses to generate a unique set of early reflections for each sound emitter, relative to the listener’s position.
Clustering Sounds to Reduce Overhead: You have a vehicle sound that is made up of a significant number of component sounds that are driven by a complex RTPC system. The components originate from different physical locations around the vehicle, so you use individual game objects for sound emitters. However, it is costly to apply Effects and spatialization per individual emitter, so you want to do this only when the listener is suitably close by. If the listener is far enough away that the subtle changes in angle are unnoticeable, you should mix all the sounds together before applying processing and spatialization to the entire group of sounds.
Master busses cannot be positioned.