If you want to add music, sound effects, or voiceovers to your cinematics in Unity then you can do so using the ”Audio Track” feature within Timeline.
Implementation of this is quite simple.
To start, just create a new empty game object within the hierarchy and add an audio source component to it.
Don’t worry about adding or changing anything to this.
It is only used to direct timeline to use this “Audio Source” when it plays the sounds.
Next, just right click within Timeline and create an “Audio Track”. Link the audio source game object to this audio track. Then drag and drop your audio file into the timeline editor beside your new audio track and done!
Now all you have to do is adjust the sound files you’ve added within timeline to coordinate accurately with your cinematic.