A COMPARISON OF ERROR SENSOR STRATEGIES FOR THE ACTIVE CONTROL OF DUCT NOISE

A theoretical comparison of a number of error sensor strategies is undertaken for active control of periodic noise in a hard-walled rectangular duct. Error sensor strategies investigated include the minimization of pressure at a point, the total real acoustic power output, and an estimate of the acoustic potential energy. A new error sensor strategy is also proposed and investigated. The strategy is based upon minimization of the power flow determined by a modal decomposition of the duct sound field. The error sensor strategies are analyzed for both plane-wave and multimode sound fields, and for a range of duct termination conditions. The criterion used to assess the error sensor strategies is the minimization of the sound field downstream of the control sources.