Abstract: Soundproofed conduit to discharge fumes, advantageously associated with assemblies to discharge fumes for melting systems in steel production plants, the conduit being located between the ventilation system (14) and an outlet chimney (13), at least the first segment (19a) of the discharge conduit defining a section with a value (A) through which the fumes transit, the conduit (12) defining a path, from the relative ventilation system (14) to the discharge chimney (13), comprising at least two counter-opposed and controlled changes in direction (15a, 15b) defining at least respective consecutive segments (19a, 19b, 19c) arranged one at an angle to another, the changes in direction being functionally configured so as to cause phase and counter-phase effects of the sound waves generated by the fluid in transit, the phase and counter-phase effects having the purpose of at least deadening partly the sound waves caused by the passage of the fluid.