The Sound Manager Global Rate Event.
This event is dispatched by the Base Sound Manager, or more typically, an instance of the Web Audio Sound Manager,
or the HTML5 Audio Manager. It is dispatched when the
rate property of the Sound Manager is changed, which globally
adjusts the playback rate of all active sounds.
Listen to it from a Scene using:
A reference to the sound manager that emitted the event.
The updated rate value.