抄録
Sound Absorption of Granular Material had not evaluated, because it seems that the sound absorption effect of granular material is very small. But it is well known that the noise levels in train tunnels are on the increase caused by changes of railways from ballast to slab. This study tries to measure sound absorption effects and airflow resistances and to evaluate the horizontal incident sound absorptions of granular materials. The sound absorption of granular materials increases according to the airflow resistances. The tendency of it is the same with tendencies of porous materials. It is confirmed that the sound absorption effects paved with granular materials in the test pipe.
