Embodiments relate to a plastic wall panel, comprising a hollow body having external walls and defining an internal cavity. The external walls include: a first major side wall, a second major side wall opposite the first major side wall, a minor top wall, a minor bottom wall, a first minor end wall and a second minor end wall opposite the first minor end wall. The minor top wall and the minor bottom wall each define mating structure to mate and align with another adjacent panel so that multiple panels can be tiled together to form at least part of a sound attenuation barrier. The hollow body defines a passage extending between the first and second major side walls and through the first and second minor end walls to receive a reinforcing beam.

Embodiments relate to a plastic wall panel, comprising a hollow body having external walls and defining an internal cavity. The external walls include: a first major side wall, a second major side wall opposite the first major side wall, a minor top wall, a minor bottom wall, a first minor end wall and a second minor end wall opposite the first minor end wall. The minor top wall and the minor bottom wall each define mating structure to mate and align with another adjacent panel so that multiple panels can be tiled together to form at least part of a sound attenuation barrier. The hollow body defines a passage extending between the first and second major side walls and through the first and second minor end walls to receive a reinforcing beam.

The sound absorbing board includes a body and multiple sound absorbing elements. The body has a first side surface and a second side surface. The multiple sound absorbing elements are formed on the body at spaced intervals, and each one of the multiple sound absorbing elements has a protrusion, a groove, and two sound absorbing openings. The protrusion is formed on the first side surface of the body. The groove is formed on the second side surface of the body and has multiple concave portions and at least one convex portion. The multiple concave portions are formed on a bottom surface of the groove. The at least one convex portion is formed on the bottom surface of the groove, and is formed between two adjacent ones of the multiple concave portions. The two sound absorbing openings are formed on the two opposite side surfaces of the protrusion, respectively.

A sound wall and a method of constructing the sound wall. The sound wall includes a pair of laterally spaced posts, at least one of the pair of posts including: an elongate central member, a flange extending form the elongate central member in a direction substantially normal to the elongate central member, and a fin extending from the central member. The central member, the flange, and the fin may define a cavity for receiving elongate panels. The sound wall may include a plurality of elongate panels extending between the laterally spaced posts and stacked in an elongate direction of the elongate central member. End regions of the respective elongate panels may be retained between the flange and the fin. The sound wall may include an elongate stiffener member positioned within at least one of the plurality of elongate panels.