Active noise suppression of smart panels including piezoelectric devices and absorbing materials

In this paper, noise reduction performance of piezoelectric smart panels is experimentally studied. Piezoelectric smart panel is comprised of plate structure on which piezoelectric sensor/actuators are bonded and sound absorbing materials. The concept of piezoelectric smart panels is to combine passive and active strategies such that the noise reduction can be effectively achieved over a broad frequency range. The noise reduction performance is tested on an acoustic tunnel. The tunnel is made of a guided tube having a square cross section and loud speaker is installed at one end as a sound source while nonreflection terminator is attached at the other end. The panels can be mounted in the middle of the tunnel and the transmission as well as reflection of panels can be measured. Noise reduction performance of a single plate with absorbing material shows a good result at mid frequency region but little effect in the resonance frequencies. When the active control scheme is activated, a remarkable noise reduction is observed at the resonance. The combined use of absorbing materials and piezoelectric active devices brings the simultaneous noise reduction in mid and low frequency regions. It can be concluded that piezoelectric smart panels incorporating passive absorbing material and active piezoelectric devices, is a promising technology for noise reduction in a wide band frequency.