An aerator having a duct and a deflector member to deflect the flow of air leaving the duct, the deflector member being mounted movably relative to the duct by means of an articulation. The deflector member extends around the articulation. The articulation includes a male part having a head and a female part having a housing, the head being received in the housing to allow the adjustment of the deflector member relative to the duct. The female part further includes at least one pressing element biased to bear against the head by an elastic biasing element.