Acta Acustica united with Acustica vol:85 issue:4 pages:538-546
The present study addresses the reduction of the sound transmission through a double panel test section by means of an active noise and vibration control system. This stiffened double panel can be seen as a section of an aircraft fuselage, whereas the active control system has to reduce the noise level inside the passengers' cabin generated by the incident sound waves from the propellers. Experiments prove that control loudspeakers and error microphones in the cavity between both panels yield higher reductions in the radiated sound power than control shakers and error accelerometers on the radiating panel. This conclusion remains valid when the receiving and the radiating panel are mechanically connected by means of four vibration isolators, and when the cavity is filled with thermal insulation blankets. It also appears that, in case of an active cavity noise control system, there exists an almost linear relation between the reduction of the acoustic potential energy in the cavity and the reduction of the radiated sound power. The optimised control system performs much better than a control system with sensors and actuators in arbitrarily chosen positions. The experimental results of this study are interpreted in the light of results obtained by other researchers on similar test cases.