Applications of the in-situ Airborne Transfer Path Analysis (TPA) technique in the diagnosis of sound transmission paths of a building element

For airborne sound transmission through building elements, the sound insulation of a building element is given as the Sound Reduction Index (SRI). SRI quantifies the sound transfer but gives no information about how the transfer takes place and what are the contributions of different sound transfer paths involved. Here we investigate the use of Transfer Path Analysis (TPA) techniques, which are fairly common to the vehicle acoustics industry, to provide additional diagnostic information. This paper formulates an in-situ Airborne TPA technique based on blocked forces to rank order the contributions of different sound transfer paths to the transmitted pressure. The application has been tested on cavity backed single leaf and dual leaf partitions excited by airborne and structure borne sources. A simplification of the method is discussed by means of measuring airborne contact forces to diagnose airborne sound transmission through single leaf walls. Finally another formulation of the in-situ Airborne TPA is described to identify and quantify the reflected pressure in the source room. Using this formulation the in-situ incident pressure can be calculated which potentially allows the contribution of each transfer path to the overall SRI to be quantified whilst avoiding the use of diffuse field assumptions.