Study on the Properties of Sound Isolation for Acoustic Band Gaps Materials with Tandem Structure

The properties of band-gaps for two-dimensional phononic crystals consisting of stainless steel cylinders in air background with square lattice, triangular lattice and honey-comb lattice are investigated theoretically by the plane wave expansion (PWE) method, respectively. The lattice structures play the key role in determining existence of band gaps. According to the width and position of band gaps and directions of lattices, we have designed a new type of acoustic band-gap materials with a tandem structure of three kinds of lattice structures and obtained the ultrawide band gaps within the human audible range of frequencies. So this composites with a tandem structure can stop effectively the effect of environmental noise as noise barriers.