Nightingale floor
A Nightingale Floor ( Jap.鴬張り, uguisubari ) is a wooden floor that makes a chirping sound with every step and thus betrays intruders.
The tones are created when the floor is stepped on by displacements of tenons with which the floorboards are attached.
The sound is similar to the chirping of the Japanese nightingale ( Japanese bush warbler ). This explains the name of the floor. This form of the "alarm system" can be found, for example, in the Nijō-jō , the Eikan-do and the Chion-in temple in Kyoto .