Acoustic based modal filtering of orthogonal radiating functions for global error sensing: Part II. Implementation

This is the second of two companion papers, which summarise the theoretical and experimental work carried Out to develop and compare a generalised acoustic based sensing strategy for radiated sound power. In this paper we focus on the implementation of an acoustic-centric sensing system; based on different orthogonal decompositions. An important consideration here is that the sensing strategy is capable of being applied to a large and complex noise source. A sensing array consisting of 128 microphones and a custom-built electronic filtering system used in the data fusion process is demonstrated. We examine different estimates of the global error criterion, radiated sound power, based on orthogonal multipole and radiation modes. The experiments are the extension of the simulations in the first part of this work, where each orthogonal constituent is filtered, in real time, from the 128 microphone signals. The estimates of radiated power are compared for a two-dimensional structure under two sets of boundary conditions. The sensing comparisons are extended to a comparison of the achieved global attenuation when each of the different orthogonal constituents are minimised by a feedforward control system. (c) 2006 Elsevier Ltd. All rights reserved.