Localization of acoustic waves in 1D random liquid media

We study acoustic propagation in one dimensional water ducts containing many air-filled blocks. The acoustic band structures for the periodic arrangements of the blocks is calculated, whereas the transmission for various random configurations of the blocks is computed by the transfer matrix method. It is shown that waves at all frequencies become localized even with a small amount of randomness. The spatial distribution of the localized energy is investigated, and is shown not to be trapped near the source, contrary to higher dimensional cases. The results also reveal a distinct collective behaviour for localized waves, a feature useful for distinguishing the localization from the residual absorption effect.