The present invention particularly relates to a method for determining physical and / or chemical properties of a medium (M) based on at least a first and a second acoustic wave, which have propagated at least partially through the medium (M) from at least one transmitter (SE1, SE2; SE3, SE4) to at least one receiver (SE2, SE1, SE4, SE3), wherein from receiving signals ( yr0, yr1; ys0, ys1) generated at the level of at least two receivers, a propagation time difference (Δt) of the acoustic waves and / or an absolute propagation delay (t0) of an acoustic wave, and by means of a determined difference in propagation time (Δt) and / or a determined absolute delay (t0), the physical and / or chemical properties of the medium (M) being determined, for example an average speed of flow (vm). According to the invention, at least two different transmission signals (x0, x1), of substantially the same base frequency (f), which have a prescribed phase difference between them and which generate a first and a second respectively, are used. acoustic wave such that, for each propagation direction, two receive signals (yr0, yr1; ys0, ys1) are generated, which are related to different transmission signals (x0, x1), and - a time difference of propagation (Δt) and / or an absolute propagation delay (t0) being determined by virtue of the four reception signals (yr0, yr1; ys0, ys1). Furthermore, a device is provided for the determination of the physical and chemical properties of a medium (M), which is in particular made and intended for the implementation of a method according to the invention.
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