Abstract
Active, semi-passive and passive noise isolations of a plate bonded with piezoelectric elements were
studied and their effectiveness is compared. The noise is generated by a loudspeaker inside a box and
transmitted to the outside through the plate. The frequency of the noise was swept around the first
resonance mode of the plate. The results show that the damping effect at the first resonance mode reaches
7.4dB with semi-passive technique, 13.5dB with active technique and 8.2dB with passive technique. The
influence of sweeping speed on the control performance of each approach was investigated, and a large
decrease of performance was observed for semi-passive control (70% of decrease) at the sweeping speed
of 200Hz/sec. A decrease of 30% is observed in case of active control, whereas there is almost no decrease
of performance with passive technique. Increasing the excitation level leads to non-linear behavior of the
plate inducing a much lower damping. The influence of excitation level on the control performance of
three approaches was investigated. The results show that all these three techniques are easily affected by
nonlinearity.
