## Radio Deception: The Art of Imitation
The recordings used in sonic operations were made at Fort Knox, capturing specific acoustic signatures: tank tread grinding, engine rumble, convoy movement, the mechanical noise of bridge-section assembly. These were assembled into soundscapes matching specific scenarios. Playback equipment was mounted on halftracks. Under favorable atmospheric conditions the sound could carry up to fifteen miles. Night was preferred, both for concealment and because sound carries better in cooler nighttime air. Timing had to coordinate with the visual and radio elements: a sonic display suggesting bridge construction at a location where the visual deception had placed infantry rather than engineers would be internally inconsistent.
## The Human Element: Patches and Bar Talk
Military Morse operators of the period developed individual fists — the characteristic rhythms and timing of their sending style — that experienced telegraphists could recognize. The Signal Company Special operators trained to imitate these individual styles from recordings. Beyond individual fist imitation, the radio deception involved creating the entire communications architecture of the impersonated unit: command nets, logistics nets, artillery nets, liaison nets, all with their characteristic traffic patterns, call signs, and volumes. When a real unit went off the air during a move, the deception operators took over its frequencies and continued generating traffic suggesting it was still in its original position.
## Operation Metz and Plugging Gaps
When the 23rd impersonated a division, its soldiers wore that division shoulder patches and its vehicles carried the impersonated unit insignia. Men were also sent to local bars and cafes with instructions to drop false information within earshot of potential German agents — classic tradecraft. The soldiers chosen for this role had to know enough about the impersonated units to answer casual questions without raising suspicion. The information they let slip was carefully scripted to reinforce the main deception message.