An acoustic absorption cell including a bottom wall extending in a plane orthogonal to an axial direction, an enclosure including a first axial end secured to the bottom wall, and an acoustic horn extending inside the enclosure between a first opening of the horn and a second opening of the horn smaller than the first opening, the horn being secured to a second axial end of the enclosure opposite the first axial end, and the first and second openings of the horn each extending in a plane orthogonal to the axial direction. The horn includes at least one retaining arm protruding from the horn inside the enclosure and fixed to the bottom wall or to the enclosure.