Grain size and polydispersity or sorting in unconsolidated rocks are related with the mechanisms and distance of transport from sediment sources to deposits locations or basins. Due to this fact, grain size distributions are an important signature of sedimentary bodies. In this work we present a numerical study based on solving the detailed granular dynamics for acoustic wave propagation in dry polydisperse granular ensembles. The granular samples are generated by simulating natural processes of sedimentation and are characterized by the second cummulant of the grain size distributions corresponding to a realistic scenario. Ultrasonic seismic wave attributes are compared between groups with different polydispersity. Dissimilar groups reflected distinctive seismic attribute properties. This indirect wave signal study could lead to a seismic description of probable sediment distances and transport mechanisms for unconsolidated rocks.