Brake booster

The invention relates to a pneumatic brake booster for a motor vehicle having a booster housing, the interior space of which is divided by at least one axially movable wall which can be loaded with a pneumatic differential pressure into at least one working chamber and at least one vacuum chamber, wherein the movable wall comprises a diaphragm plate and a rolling diaphragm which is arranged sealingly between the booster housing and the control housing, having a control valve which controls the differential pressure, is arranged in the control housing, and which controls a connection of the working chamber to the vacuum chamber or atmosphere, having at least one extraction duct which is integrated into the control housing for connection of the vacuum chamber to the working chamber, wherein the extraction duct can be blocked by the control valve. In order to improve the noise behaviour during operation of the brake booster, in particular during the return of the control housing, it is proposed to provide means for influencing fluid dynamics in the extraction duct 10 between the vacuum chamber 5 and working chamber 4.