Multi Audio Listener

The Problem

Unity does not allow to have multiple `Audio Listeners`, which makes sense in most of the games - you have only one player (per physical machine) that is able to _hear_ sounds. The problem shows up when you have local co-op game with multiple players on single machine.

The Solution

The solution in big picture is to create one `AudioListener` that's located in the middle and same number of `AudioSources` as there are `MultiAudioSource`. Each time interval real audio sources moves in a way to mimic what would hear the closest player to the game object with the `MultiAudioSource`.

DEMO http://MultiAudioListener.napad.games