Diaphragm control valve device for controlling a gas flow, comprising a valve body with an opening through which the medium can flow in the direction of flow and which is bounded by a circumferential surface in the valve body lying parallel to the direction of flow, a diaphragm slidably disposed in a gap within the valve body perpendicular to the direction of flow to affect the flow through the orifice, the gap separating the circumferential surface into an inlet-side and an outlet-side partial circumferential surface , wherein the outlet-side partial circumferential surface follows the inlet-side partial circumferential surface in the direction of flow, and wherein the outlet-side partial circumferential surface has a first edge facing the diaphragm and a second edge facing away from the diaphragm , wherein the diaphragm has a lower edge which is arcuate, preferably part-circular or part-elliptical; characterized in that the first edge has a plurality of geometric features for reducing noise emission, which are designed to make the first edge non-uniform, the geometric features being provided in a region of the outlet-side partial circumferential surface which is adjacent to the region of the gap into which the diaphragm dips when the opening is closed, and the geometric features being designed as recesses in the outlet-side partial circumferential surface which are open towards the first edge , wherein said plurality of geometric features are provided in a region of said partial circumferential surface that is flowed against when said orifice is 40% open, wherein 0% corresponds to a complete closure of said orifice by said orifice . a valve body with an opening through which the medium can flow in the direction of flow and which is bounded by a circumferential surface in the valve body lying parallel to the direction of flow, a diaphragm slidably disposed in a gap within the valve body perpendicular to the direction of flow to affect the flow through the orifice, the gap separating the circumferential surface into an inlet-side and an outlet-side partial circumferential surface , wherein the outlet-side partial circumferential surface follows the inlet-side partial circumferential surface in the direction of flow, and wherein the outlet-side partial circumferential surface has a first edge facing the diaphragm and a second edge facing away from the diaphragm , wherein the diaphragm has a lower edge which is arcuate, preferably part-circular or part-elliptical; characterized in that the first edge has a plurality of geometric features for reducing noise emission, which are designed to make the first edge non-uniform, the geometric features being provided in a region of the outlet-side partial circumferential surface which is adjacent to the region of the gap into which the diaphragm dips when the opening is closed, and the geometric features being designed as recesses in the outlet-side partial circumferential surface which are open towards the first edge , wherein said plurality of geometric features are provided in a region of said partial circumferential surface that is flowed against when said orifice is 40% open, wherein 0% corresponds to a complete closure of said orifice by said orifice . <EOS>