Experiments on Structural Control of Sound Transmitted Through an Elastic Plate

Active control of sound transmission through an elastic plate has been experimentally studied. The control was applied directly to the plate by point force vibration inputs while the error information and performance was measured in the radiated acoustic field by discrete microphones. Test cases were also performed in which the error sensors were accelerometers mounted on the plate. A time domain LMS adaptive algorithm was used as the basis of the control system design. The results show an impressive increase in plate transmission loss over a wide range of frequencies with a maximum of two control shakers. The advantages of using error information derived from the radiated acoustic field rather than structural response is demonstrated. The mechanisms behind the efficiency of this control approach are discussed.