Experimental Validation of the Active Noise Control Methodology Based on Difference Potentials

Abstract

To achieve active noise cancellation over a large area, it is often necessary to get a measure of the physical properties of the noise source to devise a counter measure. This, however, is not practical in many cases. A mathematical approach, the difference potentialmethod, canprovide an alternative solution for active shielding over a large area. In this approach, the cancellation of unwanted noise requires only measurements near the boundary surface but not at the source itself, and no other information is required. Moreover, the solution based on difference potentials applies to boundeddomains in the presence of acoustic sources inside the domain to be shielded. This paper reports on the results of experimental validation for themethodology. It has beendemonstrated thatwhile preserving the wanted sound, the developed approach can cancel out the unwanted noise. The volumetric noise cancellation offered by the proposedmethodology, alongwith leaving thewanted sound unchanged, is a unique feature compared with other techniques available in the literature. It can be most useful in the context of applications related to civil aviation, in particular, for eliminating the exterior noise inside the passenger compartments for both current and future generations of commercial aircraft. Nomenclature bvol = force per unit volume Cd = loudspeaker dipole calibration constant