StereoPannerNode
The pan property takes a unitless value between -1 (full left pan) and 1 (full right pan). This interface was introduced as a much simpler way to apply a simple panning effect than having to use a full PannerNode.
var StereoPannerNode: {
prototype: StereoPannerNode;
new (context: BaseAudioContext, options?: StereoPannerOptions): StereoPannerNode;
};