Sounds like you’re starting from the very beginning. There are lots of starting resources out there, including a very nice book by Richard Stevens and Dave Raybould.
Generally, you want to think of Game Audio as an Event based system.
An Event happens which triggers a Sound playback
or
an Event happens which changes Sound parameters.
If you want to modify an existing project, then you need to figure out where sounds are triggered from and how the systems that are part of the gameplay work in the greater context (sometimes player input, sometimes other things, like indeterminate game events).
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In the case of the Elemental Demo, sounds are triggered on a Matinee Timeline–which triggers Events over time.
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