is continuously reduced with each further individual pressure pulse so that the interval between the last two individual pressure pulses is shorter than the distance between the first two individual pressure pulses this becomes clear from a simple numeric example for a pressure medium pulse consisting of three individual pressure pulses while the second individual pressure pulse follows 100 ms after the end of the first individual pressure pulse the third individual pressure pulse follows just 60 ms after the end of the second individual pressure pulse further impetus for calculation of the time interval between the individual pressure pulses can be found by the person skilled in the art in de 197 55 064 b4 mentioned above with regard to specification and implementation of the pressure level of the individual pressure pulses of a pressure pulse series the simplest variation can be to provide all of the individual pressure pulses of this time sequence with the same pressure level in a more complex variation however the pressure medium pulse can also be predetermined or configured as a time sequence of several individual pressure pulses with variable pressure level in this case it can be provided that the pressure level of the individual pressure pulses continuously decreases with each further individual pressure pulse so that the pressure level of.