Advanced time domain wave-number sensing for structural acoustic systems. II. Active radiation control of a simply supported beam

A real time structural acoustic sensor and associated signal processing is developed and applied to the active control of sound radiated by a simply supported beam. The sensor consists of multiple accelerometers mounted on the structure. An array of FIR filters processes the measured structural information to provide an estimate of the structural wave-number component coupled to acoustic radiation in a prescribed direction. This time domain signal is used as the error information in a feedforward adaptive control approach. The single channel filtered-X LMS algorithm is implemented here. Computer simulations in the discrete time domain demonstrate the ability of the sensor to replace the use of error microphones in the far field. The described sensor represents a significant alternative to the use of distributive structural sensors (for example piezoelectric material) by providing accurate radiation information over a broadband frequency range.