A method for mounting an acoustic panel on the inner surface of an annular housing of an axial turbomachine, the cylindrical acoustic panel comprising at least one longitudinal slot so as to define two opposing ends, the method comprising: bringing the two opposing ends closer together so as to reduce the cylinder radius of the acoustic panel; inserting the acoustic panel into the fan casing when the opposing ends are close together; deploying the opposing ends so as to increase the cylinder radius of the acoustic panel; and securing the acoustic panel to the housing by gluing.