Experimental results using active control of energy density

Abstract

Previous research reported has presented numerical results obtained, indicating that one can often achieve improved global control of an enclosed acoustic field by minimizing the acoustic energy density, rather than the acoustic pressure. Inexpensive sensor probes have been developed that are capable of sensing the pressure and velocity components of the acoustic field, for incorporation into an adaptive control system that minimizes the energy density. The control system has been implemented within an enclosed sound field and has been used to compare the global attenuation achieved by minimizing either the squared pressure or the energy density. The control system is capable of implementing control with multiple sources and/or sensors. Results are shown for the low modal density case in the enclosure and indicate the improved global attenuation that can be achieved using energy density control. As well, the dependence of the controlled field on error sensor location is shown to be substantially weaker when controlling energy density than when controlling squared pressure. [Work supported by NASA Langley Research Center.]