Acoustic metamaterials are of growing interest due to their ability to manipulate the propagation of acoustic waves in an extraordinary manner to benefit various applications, such as communications, biosensing, and medical diagnosis and therapy. Among various construction methods of acoustic metamaterials, artificially engineered elastic periodic structures, known as phononic crystals (PCs), are the strongest candidates since they exhibit complete phononic band gaps and negative refractions due to the periodicity of the structure. In this book, a new class of acoustic...