Experience Designer
There are a couple of hidden gems that will allow you to quickly build some neurofeedback apps. You can change the global volume, or screen brightness by inserting a node (there's also a secret update if you can find it). To do so just change the variable (from 0 to 1) for the following nodes:
Set a custom feedback node to Volume or MasterVolume for all audio between 0-1 and it will change the audio in the experience.
Set a custom feedback node to ScreenBrightness between 0-1 and it will change the brightness of the experience UI.
