Abstract:

Active control of noise inside an enclosure from exterior noise sources is accomplished by the use of piezoelectric actuators and either piezoelectric or MEMS sensors placed on the enclosure wall. It is generally known that this approach provides very good results at the resonant frequencies of the cabin walls and if the excitation noise is at a single frequency. In the present study, broadband excitation is looked at from the exterior, in the time domain. A sensor mounted on the cabin wall provides the reference signal for the excitation; the error sensor can either be the piezoelectric sensor on the wall or a sound-level meter placed at an appropriate position inside the cabin. Different types of closed loop control are attempted using both analog and digital strategies. The study examines the number and placement of actuators on the wall relative to bandwidth of the external source, as well as control of wall vibration as a means of controlling the radiated noise.