  Propagation of acoustic waves in an one-dimensional water duct containing
many air filled blocks is studied by the transfer matrix formalism. Energy
distribution and interface vibration of the air blocks are computed. For
periodic arrangement band structure and transmission rate are calculated
analytically, whereas the Lyapunov exponent and its variance are computed
numerically for random situations. A distinct collective behavior for localized
waves is found. The results are also compared with optical situations.
