Method for producing an acoustic treatment panel

A method for producing an acoustic treatment panel, the method comprising:

• assembling first and second plates, at least one of which is deformed so as to separate the plates locally to form a plurality of cavities of a cellular structure between the first and second plates, said cavities being delimited by a plurality of facets and a plurality of partitions formed by at least one of the deformed plates,
• producing at least one opening on the facets of one of the first and second plates,
• pressing an acoustically resistive plate against the surface of the cellular structure including the openings;
• forming the first and second plates so as to form first and second cellular half-structures each with a set of co-planar facets separated by a grid of grooves, the first and second cellular half-structures having identical grids of grooves, and
• assembling the first and second cellular half-structures by pressing the ends of the grooves of the first and second half-structures against each other.