Abstract: A device for controlling a propagation direction of noise, which is preferably associated with a sound insulating wall to significantly improve its sound reducing effect of alleviating noise emitted from a noise source such as a railroad, highway and the like on which an electric car and automobiles run. The device comprises a hollow structural body composed of a plurality of elongated vertical hollow passages arranged at right angles to a substrate and spaced apart from each other by means of partition walls. The upper noise inlet side surface of the hollow passages face a propagation direction of noise emitted from the noise source and serve to refract and lag in phase the noise passed therethrough, thereby producing a sound reducing region located intermediate between a direct sound propagation and the refracted sound propagation. In one embodiment, a pair of hollow structural bodies are arranged in opposition to each other to form an arch type device.

Abstract: A noise control device which produces behind it an enlarged sound reducing region is disclosed. The device comprises a hollow structural body composed of a plurality of elongate hollow passages which are different in length and constructed such that the passage length is made the longest at a substantially center part in a vertical direction and is made gradually shorter from the center part toward upper and lower edges of the hollow structural body. The upper and lower edges allow direct propagation sound emitted from a noise source to pass thereover and therethrough.