Foreground and background sound effects need to be controlled carefully and blended properly, so that background noises such as music and sound effects do not distract from the speech.

The values for this comprise a URI value and an optional controlling parameter. The value should be space-separated.

The URI specifies an audio file to be downloaded and played in the background.

The following keywords control how the background sound is mixed with any parent object's sound effects:

• mix

• repeat

• auto

• none

The mix keyword combines any sounds already playing as defined by parent elements.

The repeat keyword allows for the background sound to be looped as required to extend it to the same length as the spoken content.

The auto value allows the parent elements sound effects to be played without being interrupted by this elements sounds.

The none value turns off any sound effects inherited from parent objects only playing sounds controlled by this object.

Warnings:

• This is not yet supported by any of the browsers.