This animal specie is a carnivore, and they hunt in packs. Their communication is pretty much based on sound, and they rely on mimethism to remain unnoticed. They prevail on their prey by number, not by size.
They have developed a fancy ability: by having two larynxes and two mouths (or the anatomic equivalent of the structure devoted to sound emission) to emitt sounds, they can strongly improve the directionality of their vocal emission by manipulating sound interference. In this way they can achieve that while their prey hears a flimsy whisper, their pack hear a clear shouting.
Would this be realistic under current known laws of physics? Are there any shortcoming?