A multichannel active system for control of the booming inside a van

The van under study presents a problem of booming when the engine periodic noise excites some low‐frequency modes of the cabin. The aim of this work is the design and implementation of a multichannel active system to alleviate this problem. First, a reference signal is searched correlated with the noise measured by a microphone in the driver head position. The best reference signal is the longitudinal vibration picked up by an accelerometer under the differential group. Then, the acoustic field inside the van is modeled by the normal modes theory. Optimization by simulated annealing allows one to find the best locations for six loudspeakers and six microphones. Finally, the multichannel active noise control is implemented by using a commercial system. Measurements of noise reduction have been carried out in the semianechoic room at NECT‐E under usual driving conditions (third gear, slow acceleration). [Work supported by CICYT, Project AMB97‐1175‐C03‐01.]