A sound absorbing panel comprising a generally rectangular mat of sound absorbing material, a plastic non woven covering at the frontal mat surface facing towards the sound insulated space and a sheet metal plate covering at the rear. The sheet metal plate covering extends outwardly perimetrically around the mat and forms uniformly sized flange extensions bent inwardly by 180.degree. to form lip portions and corresponding recessions between the flange extensions and associated lip portions. Four Z section edge members are employed, one for each of the four lateral sides of the mat, each Z section edge member comprising a base portion abutting the lateral side of the mat and two spaced apart flange portions projecting in opposite directions from the base portion, one of these flange portions entering within the abovementioned recessions of the sheet metal plate covering wherein it is being pressed to form a compact frame structure perimetrically around the sound absorbing panel.