The acoustic band structures have been computed for cubic arrays of spherical hydrogen balloons in air. Stop bands are obtained for the face-centered-cubic (fcc) and body-centered-cubic (bcc) lattices, however, there is no band gap for the simple cubic lattice. These gaps are largest for a volume fraction of ∼38% and, at low balloon pressure (1.10 atm) and small latex wall thickness (10−3times the inner radius), the corresponding gap/midgap ratios are about 0.2 for the fcc and 0.1 for the bcc structure. As the pressure or wall thickness increases, the stop bands diminish and ultimately vanish.