A flowmeter and filter assembly for spirometry have a flowmeter with a turbine rotor and sensor means for detecting the speed of rotation of the rotor, and a filter upstream of the flowmeter. An air-conveying device modifies the direction of the flow of air at an outlet from the filter to set the rotor in rotation within the flowmeter. The air-conveying device is integrated in the filter instead of in the flowmeter.
