Sonic horns are used to enhance the collection efficiency of mechanical shaker and reverse-air fabric filters. It utilises compressed air to vibrate a metal diaphragm, producing a low frequency sound wave from the horn bell. The number of horn required is determined by fabric area. It activates approximately 10 to 30 seconds during each cleaning cycle. It reduces the residual dust load on the bag. This decreses the pressure drop across the filter fabric by 20% to 60%. It also lessens the mechanical stress on the bags resulting in longer operational life.