Ninja Eavesdropping Technology – Technical Surveillance in History
High school students here have figured out the mechanisms of a medieval eavesdropping technology that was among the most important tools for ninja on espionage missions.
The primary mission of ninja, also called “shinobi” (the stealthy), was to gather intelligence for their lords, often using a metal plate called “saoto-kikigane,” which literally means “metalwork for listening to faint sound.”
Made of brass or other materials, the plate typically measured about 4.5 centimetres long, 3 cm wide and 3 millimetres thick.
The students concluded the saoto-kikigane made human voices more audible by blocking the high-pitched sounds through a “noise-cancelling” effect.
Their lab tests showed the device made human voices twice more audible.
Full details in the linked article below.
Fascinating to examine how eavesdropping tools and techniques were used. Knowledge has always been an important commodity, throughout history. Stealth eavesdropping technology and methods were as important in the past as they are today.
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