In this tutorial I will show you the following:
-Setting up a custom audio engine graph
-Making the 3D sound HRTF enabled for more depth and realism
-Adding a reverberation factor to the environment
-Wiring up the audio engine with filters, and understanding the graph structure
-Using KVO (Key Value Observer) patterns
As usual, you can find the example file here (https://github.com/triple7/SceneKit-with-playground-tutorials) and download tutorial4.zip.
I recommend you try adding your own sounds, like a set of samples from a logic pro x set of loops, place your instruments around like a jazz band, and add them all to the graph with filters, and maybe even place various people in the back to give the smoky jazz club of the 30s ambience you can walk around.
Enjoy