The edges of the cone can be extended with some rigid flat material, so that it is necessary for sound waves from the rear to travel out to the edges of the material before they can meet the sound waves from the front and interfere with them. The added material is called, a baffle, and its principle is illustrated in Fig. 5.2.
With the speaker alone, Fig. 5.2 (a), the front and rear waves must travel only along one side of the cone to meet at the edge. This path is so short that a speaker alone without baffle will usually not reproduce much below about 350 Hz. Fig 5.2 (b) shows the situation with a baffle added. The length of the interference path is increased by the width of the baffle material on each side of the cone.
Baffles should ...