Engineering acoustic band gaps

By using a perturbative approach, we propose a simple, systematic, and efficient method to engineer acoustic band gaps. A gap can be enlarged or reduced by altering the microstructure according to the field-energy distributions of the Bloch states at the band edges as well as their derivatives. Due to the structure of the acoustic wave equation, the engineering of acoustic band gaps is much more efficient than that of photonic band gaps. The validity of the proposed method is supported by multiple-scattering calculations. Our method makes the acoustic band gap "designable."