to provide a foamed plastic provided with holes having a specified area at a specified aperture ratio . the holes are either a through - hole or a non - through - hole and properly provided . the foamed plastic is superior in sound absorbing property and has a strength . in the case of non - through - holes , the foamed plastic can beep a sound absorbing effect as well as a sound intercepting effect , and for example , when used as a cushioning material of collision to be used as the lower portion of a dash panel of a motorear , not only the cushioning of collision but also the absorption of noises from an engine can be achieved . on the other hand , a foamed plastic obtained by pre - foaming foamable beads and again foaming the pre - foamed beads is a foamed plastic having gas permeability , which is different from usual foamed plastics . in this case , when an air current resistance value is set within a specified range , an audible sound of a human being can be most effectively absorbed . thus , the latter foamed plastic can also be used as a cushioning material of collision and the like similar to the former foamed plastic .