Noise emission is often considered to be one of the major drawbacks of fluid power systems. One of the main sources of noise is flow ripple generated by positive displacement pumps. This paper is concerned with the problems of modelling and measurement of flow ripple with emphasis on measurement techniques.Measurements are performed according to the so-called “Two-Microphone Method”. This technique makes it possible to determine the source characteristics of the pump, i.e. both the source flow and source impedance. The technique is described in detail.Measurements have been performed on a piston pump equipped with a number of different port plate geometries. Experimental results are compared with results obtained from numerical simulation.