M.HANSAKA, N.MIFUNE
We have developed a new style acoustic absorptive material suitable to be installed on railway track, named "OTOMATE". OTOMATE is made of small inorganic particles such as silica bound with small contents of epoxy resin. As the results of experiments to make clear the acoustic absorptive properties of OTOMATE, we have revealed that the acoustic absorptivity of OTOMATE has a great dependency on diameters of particles mainly due to change of flow resistnace and appropriate diameters of particles are chosen in the range from 0.5mm to 0.9mm.