The development of sound absorbing materials using natural bamboo fibers

摘要

An acoustic material has been newly developed from the viewpoint of environmental protection. For this purpose, we used a natural resource, bamboo fiber, to manufacture sound absorbing material. In this paper, the normal incidence sound absorption coefficient of bamboo fiber material was measured at the influences of thickness, air space depth, apparent density and the bamboo fiber diameter using an impedance tube. In addition, the characteristic impedance and the propagation constant of the materials were measured. The results showed that the bamboo fiber material has acoustic properties equivalent to those of glass wool. The sound absorption coefficient increased with an increase in density. We also attempted to find the best combination of samples of different densities to improve the sound absorption effects. A high sound absorption coefficient was obtained when higher density material was placed on the side of the sound source. Also, a fiberboard was made using the bamboo fiber to create the surface material of the bamboo fiber material, and was compared with plywood of the same density. The sound absorption coefficient of the bamboo fiberboard and the resonance-type bamboo fiberboard was found to be superior, especially in the high frequency range. Consequently, fundamental design criteria have been confirmed using the newly developed bamboo fiber material for sound absorption.