Abstract
This paper proposes an active control system to reduce the sound transmission through walls without analysis of their characteristics of vibration. The system consists of the plural of control modules installed target walls which have piezo ceramic loudspeakers as a secondary source. Controling sound pressure near the wall and modules's structure make it possible that each circuit has single input and single output. As a result of the experiment of the verification that assumed application to the railway vehicle, we could recognize that the sound radiation power from the target wall was reduced over 4dB.
