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

A theoretical comparison of a number of error sensor strategies is und ertaken for active control of periodic noise in a hard-walled rectangu lar duct. Error sensor strategies investigated include the minimizatio n of pressure at a point, the total real acoustic power output, and an estimate of the acoustic potential energy. A new error sensor strateg y is also proposed and investigated. The strategy is based upon minimi zation of the power flow determined by a modal decomposition of the du ct sound field. The error sensor strategies are analyzed for both plan e-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 sourc es.