Watch Movies2Watch. "Whistle To The Empty" explores how primal, concrete forms of language give expression to abstract emotions. Whistling—historically known as "xiao"—involves shaping the lips to craft melodies and sounds capable of conveying meaning and emotion. Devotees of the art believe that the sound resonates with the natural world, bridging the past, the present, and the realm of the yet-to-come. Linguist: "Where is that whistling coming from?" Old man (after a moment's thought): "It could be from many years ago—or perhaps from many years in the future."