Abstract: A fluid flow meter comprises a pair of transducers spaced apart in the direction of fluid flow. A transmitter causes acoustic signals to be transmitted in both directions through the fluid by the transducers. A processor determines information relating to the fluid flow by monitoring the time of flight of acoustic signals received by the transducers. Part of the space between the transducers defines a flow path consisting of a flow structure having a plurality of parallel fluid flow passages which extend axially in the direction of flow, wherein the cross-sectional diameters of the passages are chosen such that substantially plane acoustic waves only are transmitted through the passages by the fluid, and wherein under working conditions that fluid flows through each passage such that the ratio of the volume flow rate through the passage to the total volume flow rate remains substantially constant with respect to the total volume flow rate.