Acoustic metamaterials (AMMs) are artificial periodic composite materials offering the surprising possibility to manipulate acoustic wave propagation in the subwavelength scale through different mechanisms.As an unusual type of dispersion relation,in particular,double-negativity can be realized using acoustic metamaterials,leading to negative refraction and the superlensing in the medical ultrasonic detection.In general,for the resonant AMMs,the negative effective mass density and effective acoustic modulus are generated by the dipolar and monopolar resonances respectively.