In April and May 2012 in-situ tests with a tandem roller were carried out on a test field near Fischamend as part of a research project performed at Vienna University of Technology. The aim of the research is to examine the motion behavior of dynamically excited rollers, with the main focus on oscillating rollers. Amongst other research activities and investigations an acoustic measurement method for the determination of the contact length between the drum of the roller and the compacted soil and the banking effect of the roller was developed. The contact length shall be used as an indicator of the modulus of stiffness of the soil. The presented thesis summarizes the tests and the acoustic measurement as well as the evaluation and interpretation of the measured data. Moreover, the theoretical background is explained and the calculated values of the contact length are compared to the measured values. The ambition is to draw conclusions from the contact length about the stiffness of the compacted soil.