| 摘要 |
827,042. Laminates; sound-insulating fibreboard &c. SOC. APPLICAZIONI GOMMA ANTIVIBRANTI S.A.G.A., S.p.A. Oct. 28, 1957 [March 18, 1957], No. 33591/57. Classes 96 and 140. A sound insulating and absorbing panel comprises a pair of mutually opposed walls (1, 2) of sheet material forming respectively the front wall and rear wall of the panel, said walls being spaced from one another, a plurality of holes (5) extending through the wall forming the front wall and a plurality of cavity resonators (4, 6) confined between the front and rear walls and responsive to at least two different acoustic frequencies, each of the resonators being in communication with the atmosphere ambient to the panel by way of at least one of said holes, and the front wall, with or without also the rear wall, being of non-planar form, e.g. undulating cross-sectional form or embossed form. As shown, the resonators are of trapezoidal cross-sectional form, being separated by transverse partitions 3 extending across the interior space of the panel at alternately opposite inclinations to the front and rear walls. Alternate resonators 4 have their bases adjacent to the front wall and are accessible through a greater number of holes 5 than are the resonators 6 which have their apices towards the front wall. The resonators 4 are filled with a suitable (e.g. fibrous) sound-absorbing filling. The rear wall may be flat. The front wall 1, rear wall 2, and partitions 3 may be of sheet-metal (e.g. aluminium), a suitable plastic (e.g. synthetic resin) or a suitable cardboard or like material, or the front wall may be of wood. Specification 822,954 is referred to. |
