A.S. Elliott

Blocked pressure based Transfer Path Analysis (TPA) method to diagnose airborne sound transfer through building partitions

Airborne sound transmission through building elements or the sound insulation of the building element is usually rated by its Sound Reduction Index (SRI) or the Sound Transmission Class (STC). SRI/STC quantifies the overall sound transfer but gives no information about how the transfer takes place and what are the contributions of different sound transfer paths involved. Such problems are fairly common to the vehicle acoustics industry and are generally tackled by TPA techniques. The paper formulates an in-situ Airborne TPA technique to quantify the contributions of different sound transfer paths to the transmitted pressure. The airborne source is characterized by its blocked pressure and its direct measurement is discussed. Results are presented for dual leaf partitions excited by an airborne source. The method has shown to be significantly faster than the Blocked force based TPA method which relies on inverse measurement methods. The accuracy of the method is closely related to the wavelength of inciden...

Intrinsic characterisation of structure-borne sound sources and isolators from in-situ measurements.

The paper addresses the problem of how to characterize vibration sources and isolators with measurements made in-situ, either on a working installation or on a test bench. For example, automotive components are often characterized by test bench measurements, but there is a need to know how they will behave when coupled to components with potentially different properties in a vehicle. Ideally all components should be characterized by intrinsic properties, which can then be transferred to other installations. In the paper, some novel in-situ measurement methods for obtaining these properties are presented. First, the active properties of a source are characterized by the blocked force measured in situ. Structural dynamic properties are represented by frequency response functions (mobilities) and it is shown how, if necessary, these may be obtained by indirect measurements, for example when access to measurement points is difficult. New results for dynamic stiffness of isolators are then presented obtained u...