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 elongate hollow passages superimposed one upon the other and spaced apart from each other. The passages are arranged in 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 propagation sound and the refraction propagation sound.