An aircraft nacelle includes an air inlet (110) with a lip (114) extended to the back by a passage (116) to channel an air flow to a drive (112), the passage having at least one acoustic treatment panel (120) that includes, from the outside to the inside: an acoustically resistant porous layer (122); at least one cell-like structure (124), whose cells are sized for acoustic treatment; and a reflective or sealed layer (126). The reflective layer includes, near the end thereof that is oriented toward the lip, a surface (130) that is angled so as to be connected to the lip. A cell-like structure (136) is in contact with the angled surface, which forms an angle less than 30° with the tangent on the acoustically resistant layer. The cell-like structure is inserted between the angled surface of the reflective layer and an acoustically resistant porous layer.