Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : July 10, 2017 - July 12, 2017
In this study, we made the acoustic meta-materials for changing sound transmission property in semi-finite field. When sound passes through a material having high density, the sound velocity becomes fast. By arranging apparent density of the materials distributed over the aperture through which the wave penetrated perpendicularly, the sound transmission path could be inclined from the nominal axis of the wavefront. At first, we devised three patterns of the acoustic meta-materials. The first pattern is formed as a series of slits. The second pattern is a two-dimensional array of square props. The third pattern is an array of cross props. The wave propagation analysis in two-dimensional free field incorporating the material was performed using the finite element method. Among three patterns, we found from the simulation that the square prop affected the sound deflection most. We then conducted sound field measurements for an acoustic meta-material composed of square prop. From the measurements, it was found that the higher the frequency, the more the sound waves are deflected, and the directivity also increased. From these investigations mentioned above, the acoustic meta-materials is thought to be effective for sound deflection control.
