Sure, sorry about that.
There’s a guide here: New Audio Engine: Quick-Start Guide - Audio - Epic Developer Community Forums
Basically you need to edit WindowsEngine.ini and add AudioDeviceModuleName=AudioMixerXAudio2. Then enable the sound utilities plugin. I don’t know if the synthesis plugin is needed but you can enable that too.
Then in the same thread there’s Getting Started with Source Effects. Create a Preset Chain (right click and Sounds) and then a Preset with the envelope follower and put that Preset in the Preset Chain. After that you need some sound file. Open the sound wave and add the Preset Chain in the Source Effect Chain slot.
Then you need to set up stuff in your BP for the character or whatever actor you’ve got. You can start with an Audio component set to the sound wave you used earlier. Then add an EnvelopeFollowerListener component. Then you need to add the Source Preset you created earlier, create a variable with the type Source Effect Envelope Follower Preset and compile. Choose the Source Preset you created in the default value.
Drag the Preset variable into the BP and from that add a Register Envelope Follower Listener node. After that you can drag from the Envelope Follower Listener component (drag it into the BP) and Assign it to OnEnvelopeFollowerUpdate. This will hook up the event dispatcher and create the custom event that the EnvelopeFollowerListener component will trigger. In my case the sound was pretty low so I multiplied the Envelope Value by 20 times so I got more of a 0-1 range. You should be able to print this value when in PIE to make sure things are hooked up correctly.
By default the audio will play by default but you can also create a timer that triggers the audio like I did in my BP above. The rest of my BPs I’ve posted above. You should be able to get morph targets from the envelope follower alone by either doing Set Morph Target in the character BP or in the animation BP anim graph Try Get Pawn Owner and cast it to the character, get the Envelope Value (set it to a variable first) and put that in a Modify Curve node. That works fine but I couldn’t get the Curve Source method to work.