A baffle is a surface, usually made of wood, in which a loudspeaker is installed. As a rule, the loudspeaker is mounted centrally.
The baffle separates the front from the back of the speaker, thus preventing acoustic short circuits.
The further the distance from the front of the diaphragm to its rear, the longer the sound propagation time. This in turn lowers the lower cutoff frequency, which is determined by the size of the baffle. It is calculated from the quotient of the speed of sound (c) to four times the distance between the loudspeaker chassis and the end of the baffle: fu = c/4xl. For an infinitely large baffle, the lower cutoff frequency corresponds to the free-air resonance of the loudspeaker.