The possibility of a broadband noise reduction by piezoelectric smart panels is demonstrated. A smart panel is basically a plate structure on which piezoelectric patches with electrical shunt circuits are mounted and sound absorbing material is bonded on the surface of the structure. Sound absorbing material can absorb the sound transmitted at the mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. Tobe able to reduce the sound transmission at low panel resonance frequencies, piezoelectric damping is adopted. A resonant shunt circuit for piezoelectric shunt damping is composed of resistor and inductor in series, and they are determined by maximizing the dissipated energy through the circuit. The transmitted noise reduction performance of smart panels was tested in an acoustic tunnel. Sound absorbing material and air gap reduces the sound transmitted at the mid-frequency region effectively while the use of piezoelectric shunt damping works at the low frequency region. As a result, a remarkable noise reduction of 9-15dB was achieved in broadband frequency. Double panel exhibits better noise reduction than other panels. This approach was also applied to the structural acoustic problem of turbulent boundary layer (TBL) induced sound radiated from a panel, and the possibility of TBL noise reduction was demonstrated. The hybrid approach of smart panels is a promising technology for noise reduction over broad frequency band.