Inverse and Reciprocity Methods for Machinery Noise Source Characterization and Sound Path Quantification Part 2: Transmission Paths

Abstract

In this article and in a forthcoming companion article some recently explored experimental approaches to the\rcharacterization of the noise source strength of machinery and to the ranking of transmission paths are reviewed.\rThey form an addition to the more conventional approaches of the analysis of noise control problems in terms of\rsource-transmission path-receiver schemes. In this first article source strength descriptors are defined both for\rairborne and for structure-borne sound. Their common basis is that the physical sources are modelled in terms of\rfictitious elementary sources, such as acoustical monopoles or mechanical point forces. In three of the four\rmethods discussed, the strength of these equivalent substitution sources is determined indirectly. Advantages as\rwell as limitations are considered. One practical advantage concerns the feature that the proposed descriptors are\rmuch less affected in strongly different installation environments than the more conventional source strength\rdescriptors. Another practical advantage is that the use of elementary substitution sources as source models\rfacilitates the very convenient application of experimental reciprocity techniques for transmission path ranking.\rValidation experiments related to applications in ships, road vehicles and office machines are briefly discussed.