That device is indeed for "communication" in the same way that a warning shot is a method of communication. This is not hyperbole, this is quite literally what the device was designed for, per the US military itself:
"AHD is a non-lethal, counterpersonnel, long-range hailing and warning device capable of producing highly directional sound beams, allowing users to project warning tones and intelligible voice commands beyond small arms engagement range. This capability helps Soldiers more effectively determine the intent of a person, crowd, vessel, or vehicle at a safe distance, potentially deterring them prior to escalating to lethal force." (http://www.pica.army.mil/pmccs/combatmunitions/nonlethalsys/...)
"AHD is a non-lethal, counterpersonnel, long-range hailing and warning device capable of producing highly directional sound beams, allowing users to project warning tones and intelligible voice commands beyond small arms engagement range. This capability helps Soldiers more effectively determine the intent of a person, crowd, vessel, or vehicle at a safe distance, potentially deterring them prior to escalating to lethal force." (http://www.pica.army.mil/pmccs/combatmunitions/nonlethalsys/...)
and
"Acoustic Hailing Devices are designed to deny access into/out of an area to individuals, move individuals through an area, and suppress individuals." (http://jnlwp.defense.gov/Current-Non-Lethal-Weapons/Acoustic...)
("AHD" = "acoustic hailing device", the generic term for LRADs: https://en.wikipedia.org/wiki/Acoustic_hailing_device#Origin )