Central body for a turbojet exhaust channel, turbojet

A device for attenuating acoustic noise from an exhaust nozzle of a turbojet is disclosed. The turbojet exhaust nozzle includes a central body spaced apart from an external casing, defining a gas exhaust channel therebetween. The central body includes a flexible sleeve within an external wall, defining at least one resonator cavity therebetween. The at least one resonator cavity is in fluid communication with the gas exhaust channel via a plurality of orifices through at least one upstream portion of the external wall. The at least one resonator cavity and plurality of orifices compose at least one Helmholtz resonator.