Method for quantitatively determining number and size of particulate components contained by flowing medium, namely in form of a molten metal, in a vessel, in which ultrasound waves couple into the flowing medium, which waves are at least partially reflected on the particulate components, and of which the reflected ultrasound wave fractions are detected in form of ultrasonic time signals, which are used as the basis for the quantitative determination, characterized by following method steps: - coupling the ultrasound waves into the flowing medium with a waveguide coupled acoustically to an ultrasonic transducer, at least a portion of which is immersed in the flowing medium, in such manner that at least some of the coupled in ultrasound waves undergo a reflection on a wall region of the vessel that delimits the flowing medium or of a reflector introduced inside the vessel, by which an echo ultrasonic time signal assignable to the wall region or the reflector is generated, wherein the coupling of the ultrasound waves into the flowing medium inside the vessel takes place in manner focused with a primary direction of propagation orientated transversely to the flow direction of the flowing medium, with the result that the ultrasound waves are focused in a focal point along the primary direction of propagation, which focal point is located before or after the wall region of the vessel or the reflector in primary direction of propagation, on which the ultrasound waves propagating along the primary direction of propagation are incident and reflected orthogonally or at an angle, - detecting the reflected ultrasound wave fractions in the region or at the site of the coupling in, - calibrating the ultrasonic time signals on the basis of the echo ultrasonic time signal contained in each of the ultrasonic time signals, wherein the calibration includes calculation of at least one amplitude threshold function, which defines an amplitude threshold value for each detected ultrasonic time signal, taking into account the conditions under which the ultrasound waves are coupled into the flowing medium by means of at least the echo ultrasonic time signals, - capturing amplitude values assigned to the individual ultrasonic time signals, which values are greater in each case than an amplitude threshold fixed for the respective ultrasonic time signals, and - assigning the captured amplitude values to values that describe the size and number of the particulate components. - coupling the ultrasound waves into the flowing medium with a waveguide coupled acoustically to an ultrasonic transducer, at least a portion of which is immersed in the flowing medium, in such manner that at least some of the coupled in ultrasound waves undergo a reflection on a wall region of the vessel that delimits the flowing medium or of a reflector introduced inside the vessel, by which an echo ultrasonic time signal assignable to the wall region or the reflector is generated, wherein the coupling of the ultrasound waves into the flowing medium inside the vessel takes place in manner focused with a primary direction of propagation orientated transversely to the flow direction of the flowing medium, with the result that the ultrasound waves are focused in a focal point along the primary direction of propagation, which focal point is located before or after the wall region of the vessel or the reflector in primary direction of propagation, on which the ultrasound waves propagating along the primary direction of propagation are incident and reflected orthogonally or at an angle, - detecting the reflected ultrasound wave fractions in the region or at the site of the coupling in, - calibrating the ultrasonic time signals on the basis of the echo ultrasonic time signal contained in each of the ultrasonic time signals, wherein the calibration includes calculation of at least one amplitude threshold function, which defines an amplitude threshold value for each detected ultrasonic time signal, taking into account the conditions under which the ultrasound waves are coupled into the flowing medium by means of at least the echo ultrasonic time signals, - capturing amplitude values assigned to the individual ultrasonic time signals, which values are greater in each case than an amplitude threshold fixed for the respective ultrasonic time signals, and - assigning the captured amplitude values to values that describe the size and number of the particulate components.