The Plasma Acoustic Shield System, or PASS, is in the process of being developed by Stellar Photonics.
The company received a $2.7 million contract from the U.S. Government to build the PASS.
[1] It is part of a project supervised by the United States Army Armament Research, Development and Engineering Center.
The device is able to disorient an enemy using a series of mid-air explosions, and may also use "high-power speakers for hailing or warning, and a dazzler light source" [1] Its low power would mean that it would be unable to do significant damage to a specific enemy.
While it would not be classified as a weapon, because of its inability to stun or disable a target, its distracting light or explosions are hoped to impede the progress of those in its path.