An annular or semi-annular acoustic attenuation structure includes an inner skin and an outer skin, defining between them an annular or semi-annular volume, and a plurality of partitions extending in the space in a radial direction perpendicular to the inner and outer skins and in a circumferential direction. The inner and outer skins and the partitions are made of composite material including a fibrous reinforcement densified by a matrix. The fibrous reinforcement of each partition includes yarns or fibers extending into the fibrous reinforcement of at least one of the inner or outer skins.