We present an experimental study of acoustic wave propagation in
granular media made of mono-disperse spherical beads under stress
and periodically arranged. A previous work presented the
predominance of multiple-scattered acoustic waves for random
closed-packing granular media, whereas our experimental results
lead to the conclusion that the acoustical propagation in our
arrangement of spherical beads proceeds essentially from surface
waves. This provides another mechanism for the understanding of
acoustical wave propagation in granular media, that may be useful
at least to analyse weak disorder ones
