Analytical solution of active noise control in sound field with a reflective surface

The active noise control in half-free space is different from that of free space due to the existence of reflective surface. In this paper, an analytic solution model of half-free field active control system is presented. The model regards the loudspeaker and its mirror loudspeaker on the ground as a dipole in the same direction, so that its directivity distribution in the sound field can be calculated. When the location of primary source and secondary source is fixed, the model can provide the locations which are not suitable for placement of error points. The cut-off height and cut-off frequency of active control in half-free field are also provided.