Airborne sound insulation of aluminum extrusion structural walls of an urban rail train

Frame structures in urban rail trains have been manufactured with extruded aluminum panels. This study proposes prediction methods of the sound transmission loss (STL) of the aluminum extrusion panels and their combined structures with different acoustical treatment materials. The main contributions of this paper are (1) the establishment of STL calculation models of aluminum extrusions and their combined structures with damping or with fillings of sound-absorption materials; (2) proposed selection principles of damping material at aluminum extrusions surface and (3) specification of maximum size of the gap between sidewall doors or gangway less than 3 mm. Analysis method can be utilized to predict the sound insulation performance of the aluminum extrusion panels in the early design stage or suggest improvements.