Also the server have to be changed so that it can handle the sound information. Because of this the server has to guess in which direction the user will move and to pre-fetch the audio information. The GPS updates the coordinates and sends these to the server. The client receives information about different soundscapes that have to exist in a few moments, and it checks if it has samples for this stored, and if not it requests generation of these. 3D - Sound, and what it would add Sound can be used to help users finding their way around a new city using directional sound.
Directional sound is also useful to help people find each other.
Two Spirit users that are talking to each other through the Spirit system can determine the other user s direction through their voice and simply walk towards the voice. These systems are however usually based on that the user is looking forward at a screen. When the users are walking and looking around, the sound must be generated based on the head movements to prevent the sound sources from suddenly move as the users move their heads. The head movement is an important way for humans to identify the type and location of sound sources. The 3D sound generation is usually based on the principles of binaural human hearing.