The invention relates to a device and a procedure for measuring the flow of a gas or gas mixture in a flow channel (7), said device comprising a frame (10), which comprises measuring space (8), a measuring duct (6), which is mounted on the frame between the flow channel and the measuring space and which is open at both ends (2, 9) to pass the pressure wave generated by the flow from the measuring duct into the measuring space, and a measuring element (1) mounted on the frame and used to measure the pressure wave, said measuring element being disposed near the second end (9) of the measuring duct. According to the invention, the measuring duct is disposed in a substantially perpendicular orientation relative to the direction of flow the gas or gas mixture and so that it can rotate about its longitudinal axis, the measuring duct comprises a first orifice (4), which is disposed at the first end (2) of the measuring duct and faces alternately in the direction of flow and against the flow to pass a changing and cyclic pressure wave into the measuring duct, and the measuring duct comprises a second orifice (3), which is disposed in the part of the measuring duct extending into the measuring space to equalize the static pressures in the measuring space and measuring duct.