Two step optimization of secondary sources and error transducers in global active noise control in enclosures

Abstract

Global active control of sound can be achieved inside enclosures under low modal acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system, in which secon-dary acoustic sources (loudspeakers) and pressure transducers as error sensors are used, sev-eral optimisation strategies have been proposed. These strategies usually rely on partial ap-proximation to the problem, focussing on the study of number and localisation of secondary sources, without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here is based on two steps: the first is rather common with this sort of problem, and its goal is to find the best locations for secondary sources and their strengths by minimising the potential energy of the enclosure. The second step is the localisation of the er-ror transducer which assures the results of the first step. It has been analytically demonstrated that the optimum location of error transducers is at the minimum of the optimally attenuated acoustic field. Numerical validation of this principle is carried out in a parallelipedic enclo-sure.