| 摘要 |
PROBLEM TO BE SOLVED: To simply and inexpensively provide means to reduce noise in an elevator car effectively and stably by suppressing acoustic standing waves which occur in the elevator car; and to provide a structure which achieves the means.SOLUTION: Supposing that the shape of a ceiling surface as looked up from the inside of a car 20 composed of six surfaces (a floor surface, a ceiling surface, a front surface, a back surface, and both right and left side surfaces) is substantially rectangular, openings 32a are disposed on four apex parts of the rectangle, and cavities 32 are disposed on the back side of the openings 32a as viewed from the inside of the car 20. Secondary sound waves for control are output to the insides of the cavities 32, and the secondary sound waves for control are radiated to the inside of the car 20 from each of the openings 32a disposed on the four apex parts on the ceiling surface.SELECTED DRAWING: Figure 1 |
