An acoustic horn arranged to be fastened between a cabinet of a generic loudspeaker enclosure in which at least one loudspeaker is incorporated, and an outer casing suitable for covering the cabinet at least in part and for including a hole set having at least one hole, the acoustic horn having an outer face, an inner face, and an inside peripheral surface defining a through cavity formed through the thickness (e) of the horn and having an outer edge defined on the outer face and an inner edge defined on the inner face, the acoustic horn being arranged in such a manner that when the acoustic horn, the cabinet, and the outer casing are assembled together, the inner face is in contact with the cabinet in such a manner that the inner edge surrounds a diaphragm of the loudspeaker and the outer face is in contact with the outer casing in such a manner that the hole set having at least one hole of the outer casing lies inside an area defined by the outer edge, the horn thus being arranged in such a manner that the inside peripheral surface guides sound produced by the loudspeaker towards the outside via the hole set having at least one hole of the outer casing, the through cavity flaring from the inner edge towards the outer edge so as to guide sound towards at least one first direction which is orthogonal to the thickness of the acoustic horn, the flaring of the through cavity being greater in a front portion than a rear portion of the horn, the through cavity being also arranged to guide the sound forward in the first direction, the thickness of the horn being greater in its front portion than in its back portion, the acoustic horn having a shape that is symmetrical relative to a first plane parallel to the thickness of the horn and including the first direction, with the exception of fastener means for fastening it to the cabinet, which need not necessarily be symmetrical relative to said first plane, the inside peripheral surface including two first portions through which the first direction passes presents a shape that is hyperbolic when seen in section on a first plane that is parallel to the thickness of the acoustic horn and that includes the first direction, the two first portions including a first portion that faces in the first direction, and a first portion that faces in the the first direction but in the opposite direction, the inside peripheral surface further including two second portions through which there passes a second direction that is perpendicular to the first direction presents a shape that is straight and that slopes towards the outer edge when seen in section on a second plane that is parallel to the thickness of the acoustic horn and that includes the second direction, the two second portions including a second portion that faces in the second direction, and a second portion that faces in the the second direction but in the opposite direction. the two first portions including a first portion that faces in the first direction, and a first portion that faces in the the first direction but in the opposite direction, the inside peripheral surface further including two second portions through which there passes a second direction that is perpendicular to the first direction presents a shape that is straight and that slopes towards the outer edge when seen in section on a second plane that is parallel to the thickness of the acoustic horn and that includes the second direction, the two second portions including a second portion that faces in the second direction, and a second portion that faces in the the second direction but in the opposite direction.