Abstract: The invention concerns a flow metering techniques, which applies acoustic means and/or methods as embodied for an acoustic flow metering arrangement according to the invention. The flow metering can be implemented with an acoustic flow meter arrangement, which comprises a measuring section (1) provided with a sound source, at least two sound sensors and a reflector, being arranged so that the sound source of the acoustic flow meter arrangement and at least two sound sensors are arranged to mutual pre-defined distances in the measuring section. So, the determination of the sound velocity at rest (c) and the flow velocity (v), from the known distance between the sound source and the sensors, is obtainable from the values for sum (TSUM) and difference (TDIF) of the upstream and downstream transit times of sound between the sensor locations, by utilising the sound as directly propagated and as reflected.