Abstract: First, sound absorbing plates made of a hard material are fixed to both side plates of shaped steel members extending upward from a sound insulation wall at intervals that are equal to arrangement spans of the shaped steel members. Then, sound absorbing members that have been formed into a predetermined shape and length are attached to outer surfaces of the sound insulation plates.

Abstract: A sound absorbing material is interposed between an outer perforated plate and an inner plate to constitute a sound absorbing body, which has a bottom wall portion extending generally vertically, a hood portion laterally bulging from the top of the bottom wall portion to assume a semi-circular cross-section, and a top wall portion extending from the hood portion to assume a gentle convex cross-section. A cap is attached to the end face of the top wall portion, and a fixing member is attached to a lower portion of the bottom wall portion to constitute a sound absorbing device. The two sound absorbing devices having the identical structure are fixed to the outer surfaces of an upper portion of an upright sound insulation wall through the fixing members so as to assume a symmetrical fixing posture. The caps of the two sound absorbing devices are connected by a connecting member.