The programme concerning cavitation erosion initiated by NEYRTEC has extended over many years, first in collaboration with DRET and subsequently in larger collaboration with industrial concerns and EDF. Cavitation occurs in all standard hydraulic components, pumps, valves, turbines and propellers. All manufacturers of industrial machines recommend that their products be operated at a certain developed state of cavitation. Besides the inevitable presence of noise, the risk incurred is the occurrence of erosion. The behaviour of the noise emitted by a cavitating flow is similar to that of erosion in as much that the higher the flow velocity and the steeper the pressure gradient, the more intense the noise. The spatial distribution of impacts along the abscissa of the sample has a maximum, the location of which is independent of the flow velocity. IMG has developed miniature and durable pressure probes using piezoelectric crystals for the purpose of measuring impact pressures in the zone of collapse of vaporous cavities.