waves propagating almost in parallel with the longitudinal direction of the rail measurement zone or only at an oblique angle to the rail measurement zone in this way the one directional microphone 7 is oriented across the orientation of the other directional microphone 7 the electrical measurement signals generated by the force measurement devices not shown in fig2 and by the sonic measurement devices 7 are in turn relayed via the connected signal lines 8 to the analysis unit 9 where the signals are correlated with one another and or superimposed through the electronic means of the analysis unit 9 so that bearing damage or unevenness in the running area of the wheel for example can be detected in this way the correlation up to acoustic measurement signals picked up from different directions may lead to further detail findings of the damage pattern detected and may be used for a more reliable differentiation between wheel damages or wheel bearing damages fig3 shows a schematic diagram of a damaged rail vehicle wheel and a schematic diagram of the acoustic measurement signals and force measurement signals detected by means of a measurement system according to the present invention the left part of fig3 shows the wheel 3 of a rail vehicle rolling on a rail 1 in the direction of the rotating arrow the wheel 3.