Four common methods of transducer mounting that were selected for this study are illustrated
in Fig. 4.1. The first transducer was placed on a horizontal surface without any device to
hold it (Fig. 4.1a). The second one was also mounted in the same way but a loosely packed
sandbag was placed over it so that all sides of the bag were in contact with ground (Fig.
4.1b). The third transducer with attached spikes was firmly pressed into the ground such that
the base of the transducer was in direct contact with the ground (Fig.4.1c). The fourth one
was completely buried in soil, the soil being firmly compacted around and over the
transducer (Fig. 4.1d). All the transducers were connected to the respective recording units.