From Command and Conquer Wiki
Sonic repulsor fields protecting a GDI command post.
An application of
Harmonic resonance technology, sonic fields are specialized barriers developed by GDI. Continuous sonic waves are emitted from posts, creating a stationary repulsion field. These sonic walls were used to stop Tiberium from spreading, usually placed in urban Blue Zones, such as
London or
Munich.
GDI has adopted the technology for military purposes, allowing the creation of defensive fencings around key structures (such as the barracks or construction yards), preventing engineer/saboteur infiltration or sabotage.
