Okay, I understand now. The new audio engine in 4.16 has a way to set up an envelope follower so the code has been written for me already! It only outputs a float though, so I’m guessing it can’t be used with Curve Source as it is.
I was able to attach the envelope follower preset to a sound and have it change a morph target directly as the sound was playing so that works. It doesn’t allow you to use third party libraries in any way so I guess it’s a bit different but it should work for what I’m doing.