Primary nozzle of a turbomachine primary exhaust duct

A primary nozzle of a turbomachine primary exhaust duct, the primary nozzle comprising:

• a microperforated first wall, facing towards an inside of the primary nozzle, and which widens from a front as far as an intermediate zone,
• a one-piece second wall, comprising
• a microperforated internal part, which extends rearwards from the first wall and in continuity therewith from the intermediate zone, and narrows from the intermediate zone rearwards,
• an external part which faces towards an outside of the primary nozzle around the internal part, and
• a fold connecting rear parts of the internal part and of the external part, where the first wall and the internal part are fixed to one another, and
• a noise attenuating element fixed to the first wall and to the internal part, and arranged between the first wall and the external part and between the internal part and the external part.