A '''compression driver''' is a small specialized diaphragm [[loudspeaker]] which provides the sound for a [[horn loudspeaker]]. It is attached to an [[horn (acoustic)|acoustic horn]], a wideningcurved duct which serves to radiate the sound efficiently into the air. It works in a "compression" mode; the area of the loudspeaker diaphragm is significantly larger than the throat aperture of the horn so that it provides high sound pressures. Horn-loaded compression drivers can achieve extremely high efficiencies compared to direct-radiating cone loudspeakers. They are used as [[midrange driver|midrange]] and [[tweeter]] drivers in high power sound reinforcement [[loudspeaker]]s, and in reflex or folded-horn loudspeakers in [[megaphone]]s and [[public address systems]].
