Audio directional loudspeaker is a novel loudspeaker which can generate an audio signal with high directivity by utilizi摘要声频定向扬声器是利用参量阵原理，产生高指向性声频信号的新一代扬声器。
The directivity fibers on the surface, could prevent run down of the suspended solid.由于表面有方向性植毛，可有效阻止污泥的流失。