So I Almost Had It RightAfter yesterday's squeaky floor post, Kai sent in this article: Nightingale floors: The samurai intruder alarm system Japan’s had for centuries.
Here's an excerpt:
The specially constructed floors were called uguisubari. Literally translating as “bush warbler guard watch,” uguisubari are more commonly referred to in English-language texts as nightingale floors.
In installing nightingale floors, planks of wood are placed atop a framework of supporting beams, securely enough that they won’t dislodge, but still loosely enough that there’s a little bit of play when they’re stepped on. As the boards are pressed down by the feet of someone walking on them, their clamps rub against nails attached to the beams, creating a shrill chirping noise.
So this house wasn't training ninjas. It was protecting its owners FROM ninjas.