Active reduction of sound transmission in aircraft cabins: a smarter use of vibration exciters

This paper addresses an active structural acoustic control (ASAC) approach to reduce sound transmission through an aircraft trim panel. The focus is on the practical implementation of the virtual mechanical impedance approach through self-sensing actuation instead of using sensor-actuator pairs. The experimental setup includes two sensoriactuators designed from an electrodynamic inertial exciter and distributed over an aircraft trim panel, which is subject to a time-harmonic diffuse sound field. A methodology based on the experimental identification of key parameters of the actuator is proposed, wherein the vibration of the structure is estimated from the electrical signals picked up at the input terminals of the transducer. Measured data are compared to results obtained with conventional sensor-actuator pairs consisting of an accelerometer and an inertial exciter, particularly as regards sound power reduction. The decrease of sound power radiated is comparable in both cases and equals 3 dB when the panel is controlled at the excitation frequency of 363 Hz, as expected by optimal calculation for two control units.