A measuring method for measuring the particle size distribution γ and particle concentration C v in a conduit through which liquid flows , by means of a flowmeter assembly , which has at least one ultrasonic sensor , which is operatively coupled to a data processing unit and to a storage unit , comprising the steps of - arranging the flowmeter assembly at a predetermined location at the conduit through which liquid flows , thereby arranging the ultrasonic sensor at the conduit ; - using an ultrasonic sensor to emit an ultrasonic pulse impact at a predetermined time t=0 with a predetermined frequency f i , wherein the pulse impact comprises at least 10 periods; - using the ultrasonic sensor to capture a voltage signal V at a first point in time to, wherein the captured voltage V correlates with a particle size distribution γ and a particle concentration C v of the fluid in the conduit at the predetermined location; - calculating the intensity I by forming the square of a voltage amplitude; - using the data processing unit to temporarily store the intensity and time data in the storage unit ; - repeated capturing of the voltage signal V at different points in time t N , which follow the first point in time to, thereby temporarily storing the intensity and time data determined in this way in the storage unit ; - after a predetermined number of measurements in the data processing unit - determining an average intensity value I from the total amount of the stored intensity data in the storage unit , an intensity profile I N from the total temporal course of the voltage amplitude and of a variance σ, - determining an intensity moment τ and an intensity moment distribution τ N from the average intensity value I and the variance σ, as well as determining a damping parameter α, a backscattering parameter β, as well as a ratio R of intensity moment distribution τ N and intensity profile I N from the intensity profile I N , and - determining a particle size distribution γ and a particle concentration C v of the fluid from the ratio R, the damping parameter α, and the backscattering parameter β by means of an optimisation method. - arranging the flowmeter assembly at a predetermined location at the conduit through which liquid flows , thereby arranging the ultrasonic sensor at the conduit ; - using an ultrasonic sensor to emit an ultrasonic pulse impact at a predetermined time t=0 with a predetermined frequency f i , wherein the pulse impact comprises at least 10 periods; - using the ultrasonic sensor to capture a voltage signal V at a first point in time to, wherein the captured voltage V correlates with a particle size distribution γ and a particle concentration C v of the fluid in the conduit at the predetermined location; - calculating the intensity I by forming the square of a voltage amplitude; - using the data processing unit to temporarily store the intensity and time data in the storage unit ; - repeated capturing of the voltage signal V at different points in time t N , which follow the first point in time to, thereby temporarily storing the intensity and time data determined in this way in the storage unit ; - after a predetermined number of measurements in the data processing unit - determining an average intensity value I from the total amount of the stored intensity data in the storage unit , an intensity profile I N from the total temporal course of the voltage amplitude and of a variance σ, - determining an intensity moment τ and an intensity moment distribution τ N from the average intensity value I and the variance σ, as well as determining a damping parameter α, a backscattering parameter β, as well as a ratio R of intensity moment distribution τ N and intensity profile I N from the intensity profile I N , and - determining a particle size distribution γ and a particle concentration C v of the fluid from the ratio R, the damping parameter α, and the backscattering parameter β by means of an optimisation method. <EOS>