Vortex flowmeter designed to monitor and/or measure a medium flowing in a pipe, wherein said medium is at least temporarily two-phase or multi-phase, which has a first phase, particularly gaseous, with a first density and a second phase, particularly liquid, with a second density, distributed as particles and/or drops in the first phase, wherein said vortex flowmeter comprises: - at least one measuring tube which can be inserted into a pipe, - a bluff body, - a vortex sensor responding to variations in pressure, - an acoustic transducer - as well as an electronics unit, - wherein the bluff body extends in the measuring tube at a right angle to a flow direction in such a way that a flow path is formed on both sides of the bluff body, and in that at least two separation edges (14, 16) are formed on the bluff body on both sides in such a way that Karman vortices are shed during use, and - wherein the vortex sensor is arranged, in relation to a mounting position, downstream from the separation edges (14, 16) and is formed in such a way that it measures variations in pressure during use, which are converted into an electrical measuring signal, - wherein the acoustic transducer is integrally formed in the bluff body or is acoustically coupled to it in such a way that acoustic signals generated by the impact of particles and/or droplets of the second phase on the bluff body can be converted into electrical signals by the acoustic transducer, - and wherein the electronics unit of the vortex flowmeter is designed in such a way that -- it can determine a measured variable from the electrical signals provided by the acoustic transducer by spectral signal processing and/or by a statistical evaluation, wherein said measured variable is evaluated according to predefined criteria and/or -- it forms a quadratic mean value from values, captured over time, of the filtered electrical signals that are provided by the acoustic transducer, and evaluates said mean value as a measured variable, wherein the electronics unit of the vortex flowmeter is designed in such a way to determine a vortex frequency from the detected variations in pressure and, on the basis of this, to determine a flow velocity of the particles and/or droplets, and wherein the electronics unit of the vortex flowmeter is designed to determine a number and a mass of individual particles and/or droplets or the mass flow of the particles and/or droplets from the measured variable using a transmission factor to be determined by a calibration, wherein by means of said factor the kinetic energy of individual particles and/or droplets or the kinetic power of the particle and/or droplet flow is correlated to the measured variable, and on the basis of the flow velocity of the particles and/or droplets. - at least one measuring tube which can be inserted into a pipe, - a bluff body, - a vortex sensor responding to variations in pressure, - an acoustic transducer - as well as an electronics unit, - wherein the bluff body extends in the measuring tube at a right angle to a flow direction in such a way that a flow path is formed on both sides of the bluff body, and in that at least two separation edges (14, 16) are formed on the bluff body on both sides in such a way that Karman vortices are shed during use, and - wherein the vortex sensor is arranged, in relation to a mounting position, downstream from the separation edges (14, 16) and is formed in such a way that it measures variations in pressure during use, which are converted into an electrical measuring signal, - wherein the acoustic transducer is integrally formed in the bluff body or is acoustically coupled to it in such a way that acoustic signals generated by the impact of particles and/or droplets of the second phase on the bluff body can be converted into electrical signals by the acoustic transducer, - and wherein the electronics unit of the vortex flowmeter is designed in such a way that -- it can determine a measured variable from the electrical signals provided by the acoustic transducer by spectral signal processing and/or by a statistical evaluation, wherein said measured variable is evaluated according to predefined criteria and/or -- it forms a quadratic mean value from values, captured over time, of the filtered electrical signals that are provided by the acoustic transducer, and evaluates said mean value as a measured variable, -- it can determine a measured variable from the electrical signals provided by the acoustic transducer by spectral signal processing and/or by a statistical evaluation, wherein said measured variable is evaluated according to predefined criteria and/or -- it forms a quadratic mean value from values, captured over time, of the filtered electrical signals that are provided by the acoustic transducer, and evaluates said mean value as a measured variable,