Abstract: An electroacoustical flow meter for measuring flow rates in open and closed channels includes two sets of transducers, one set being positioned upstream relative to the other set. Flow rates are determined by computing the difference between upstream and downstream transit times of acoustical signals transmitted along various paths through the channel. A receiver in the flow meter monitors the acoustical signals received after each transmission. When an acoustical signal is received which has been attenuated due to disturbances such as obstructions along the signal path or interfering reflected signals, the receiver transmits a flag signal. This flag signal is utilized to minimize flow rate reading errors which normally result from such disturbances.