In a single-player game where you always see only one point of view in the game, one listener is enough. However, if multiple players can play on the same system, or if multiple views are displayed at the same time, each view requires its own listener so audio is appropriately rendered for all of these views. The Wwise sound engine supports up to eight listeners.
By default, every registered game object is assigned to the first listener only. However, the programmer has the flexibility to dynamically assign or unassign any game object from any listener.
There are many challenges to implementing audio for multiple listeners because the positioning of sound sources doesn't always make sense in relation to what each player is seeing. This is mostly caused by a game using only one set of speakers to reproduce the 3D environment for several players. Wwise offers a variety of tools and techniques to offset this limitation so that the audio experience is as realistic as possible for all players. For more information about how Wwise handles multiple listeners, refer to the section “Integrating Listeners” in the SDK.