Flowmeters and methods for a flow meter

Disclosed is a flow meter for determining a time-resolved volumetric flow. This has two ultrasonic sensors for transit time measurement, which are arranged in or on a flow tube. Between these a throttle is provided in the form of a nozzle or aperture. In addition, the flow meter has a differential pressure sensor. Advantageously, the aperture is located in the flow direction viewed in the field of an acoustic path of the ultrasonic sensors.