Abstract: A device, particularly for use with guided missiles, of a type having an intake pipe which is not fully rotationally symmetrical and is particularly semi-rotationally symmetrical, having particularly a semi-rotationally symmetrical air intake cross-section. The device prevents hum in the supersonic intakes of air-breathing reaction engines, particularly, ram jet engines, of a type which are operated with solid fuels and without regulation of the amount of air intake, the amount of fuel or the amount of thrust current flow for driving guided missiles. The construction includes a missile body having an intake pipe mounted thereon with a front opening disposed in an opening plane defining an inlet. A displacement body is mounted within the pipe in spaced relationship thereto and has a front pointed end which extends outwardly beyond the intake plane and which projects into the incoming air flow.