Verfahren zum Detektieren und Klassifizieren von Schallquellen, insbesondere von Fahrzeugen

In a method for the detection and classification of sound sources. especially of vehicles, using geophone 11-13 installed in the ground for the reception of sound signals coupled into the ground, a reception level 19 which is picked off at the geophone 11 output is compared 20 with at least one reference level, preferably to determine whether it exceeds the level. For optimum adaptation of the reference level to the special characteristic of the ground at the location of the geophones the seismic propagation speed is determined 14 from the transit time from 11 to 13 and the wave type is also determined 17 form the phase difference between outputs of orthogonally orientated geophones 11 and 12. An adaptation level for the measured seismic propagation speed is extracted from stored characteristics of the reception level 18 for the various wave type in standard ground, and the reference level is hence corrected 22.