Structuring a Bus Hierarchy

Structuring a Bus Hierarchy - Example

Wwise provides great flexibility in structuring a bus hierarchy. This means that there is no universally correct way to organize your project's sound structure. Still, the following simple example provides overall general practices for the development of a bus structure regardless of a project's mix of assets and requirements.

In the following screenshot, drawn from the Schematic View, we see a project organized under the three master busses into four Audio Busses, two secondary busses, and one Auxiliary Bus.

For the Master Audio Bus, we have the following busses:

Environmental Bus - This bus groups the various sounds the player is likely to hear based on different environmental factors, such as footsteps (the player's or other characters') on gravel, wood, or cement floors.
Music - This bus groups all the music, whether while playing in certain settings in the game or moving through UI menus outside of the game.
Voices - This bus groups most of the character dialogue.
Voices_Radio - With a lot of dialogue in this game, and many voices needing special settings to represent their sound over a radio, we've also added this bus separate from the Voices bus. Among other ways we could have organized it, we might have set it as a child bus of the Voices bus. But, although conceptually similar, the desired sound output and the mixing it would imply made it easier for us to define it as a separate bus directly under the Master Audio Bus.

To make it easier to apply adjustments to sounds based on being located in a large airplane hangar, we also added an Auxiliary Bus: Hangar_Env. This way, when the game scene moves to the hangar, we can send sounds - manually or through a game call - to this bus where we apply a reverb reminiscent of the open echo one might hear in such an environment.

For the Master Secondary Bus, we have the following busses:

Background Music - Some platforms, like Xbox One and PS4, have a separate speaker that is ideal for outputting sound not directly related to a game. In this case, we will use it for background music that is not affected by changes in gameplay.
Controller - A controller speaker which can output sounds that the player will hear more directly or, at least, distinctively. This is ideal in such cases as the clunk of the character's head hitting the wall.

	Tip
	Do not send the same sound at the same time to both a secondary and an Audio Bus! Every system has its own level of latency. Even if it's only a couple of milliseconds, the delay in two outputs of the same sound will create a noticeable dissonance.

For the Master Motion Bus, we have no child busses. In this simple project, there aren't many motion FX, just a door sliding and a window opening, so they can both be placed under the master. However, we could also have routed sound objects to the motion hierarchy. In such a case, it could be warranted to add child motion busses even with so few motion objects in the project.

	Note
	You can generate motion data from a sound object, including music files. For more information on generating motion from an existing sound object, refer to Generating Motion from Existing Sounds.

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