Inverse and reciprocity methods for machinery noise source characterization and sound path quantification, Part 1: Sources.

In this article and in a forthcoming companion article some recently explored experimental approaches to the characterization of the noise source of machinery and to the ranking of transmission paths are reviewed. They form an addition to the more conventional approaches of the analysis of noise control problems in terms of source-transmission path receiver schemes. In this first article source strength descriptors arde defined both for airborne and for structure-borne sound. Their common basis is thatr the physical sources are modelled in terms of fictitious elementary sources, such as acoustical monopoles or mechanical point forces. In three of the four methods discussed the strength of these equivalent substitution source is determined indirectly. Advantages as well as limitations are considered. One practical advantage concerns the feature that the proposed descriptors are much less affected in strongly different installation environments than the more conventional source strength descriptors. Another practical advantage is that the use of elementary substitution sources as source models facilitates the very convenieat application of experimental reciprocity technique for transmission path ranking. Validation experiments related to appplications in ships, road vehicles and office machines are briefly discussed.