A compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position. The inlet-adjustment mechanism includes a plurality of blades disposed about the air inlet, the blades being movable radially inwardly from an annular space of the air inlet wall, into the air inlet, so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. A noise-attenuator is disposed in the annular space, downstream of the inlet-adjustment mechanism, for attenuating aerodynamic noise induced by the inlet-adjustment mechanism when it is closed.