Acoustic enclosure structure allowing maximum reduction in parasitic internal and external interference to the soundwaves emitted by the loudspeaker. It includes, in combination: a) a vertical partitioned core (1) of the cellular type produced in a rigid material and arranged in the middle of the enclosure, extending from top to the bottom of the enclosure; b) a waveguide (2) enclosing the core (1) from one end to the other, in which the faces in contact with the core are cut out in such a way as to provide the best possible reflection of the internal soundwaves originating from the loudspeaker (4), the apertures of the cells of the core (1) being opposite the said cut-out faces of the said wave guide (2); c) a covering material (3) enclosing the assembly formed by the core (1) and the waveguide (2).