Identification and Control of Acoustic Radiation Modes

A formulation is given of reduced-order acoustic radiation sensors and reduced-order actuators for broadband sound fields. Methods are presented to determine these descriptions from measured data, and their application in systems for broadband active noise control is discussed. One application area is the reduction of sound radiated from plates with structural actuators and structural sensors, using measured or modeled versions of the most efficiently radiating patterns of a vibrating body, the so-called radiation modes. The second application of the radiation mode theory is in active noise barriers for the reduction of traffic noise. Without special precautions most of these systems suffer from spillover; a technique is given to arrive at good reductions at the error sensors with reduced spillover.