This extension allows the creation of splines that have an event trigger attached that gets positioned at the nearest point on the spline to the listener.
An audio spline can be created from the menu option Fabric/Extensions/AudioSpline and it will be added underneath the currently selected game object in the hierarchy tab.
The spline already creates a game object that has an event trigger component that can be used to trigger a specific sound (i.e. river). This is the game object that will be continuously (and smoothly) be moved to the nearest point in the spline from the listener.
The AudioSpline provides UI controls in the Scene window that allows to add points on either side of the currently selected point or delete it. If the whole spline is required to be moved then the Show Main Transform button needs to be pressed.