  This paper presents a theoretical analysis of the recently reported
observation of acoustic stop bands in two-dimensional scattering arrays
(Robertson and Rudy, J. Acoust. Soc. Am. {\bf 104}, 694, 1998). A
self-consistent wave scattering theory, incorporating all orders of multiple
scattering, is used to obtain the wave transmission. The band structures for
the regular arrays of cylinders are computed using the plane wave expansion
method. The theoretical results compare favorably with the experimental data.
