The paper by Jensen Li and C. T. Chan explores the existence of a double-negative acoustic metamaterial, where both the effective density and bulk modulus are simultaneously negative. This system is an acoustic analogue of Veselago's medium in electromagnetism, which has a negative refractive index. The double negativity in acoustics is derived from low-frequency resonances, similar to electromagnetism, but the negative density and modulus arise from a single resonance structure. The authors demonstrate that this phenomenon can be achieved by dispersing soft rubber in water, where the Mie resonances at low frequencies create negative bulk modulus and density. They use generalized effective medium formulas to show that under certain conditions, both the density and reciprocal of the bulk modulus decrease sufficiently to make the group velocity negative, leading to negative refraction. The study also shows that the double-negative band in the dispersion is not a result of band-folding due to Bragg scattering but is a consequence of resonances. The results are validated through transmittance calculations and are applicable even when shear wave components within the particles are considered.The paper by Jensen Li and C. T. Chan explores the existence of a double-negative acoustic metamaterial, where both the effective density and bulk modulus are simultaneously negative. This system is an acoustic analogue of Veselago's medium in electromagnetism, which has a negative refractive index. The double negativity in acoustics is derived from low-frequency resonances, similar to electromagnetism, but the negative density and modulus arise from a single resonance structure. The authors demonstrate that this phenomenon can be achieved by dispersing soft rubber in water, where the Mie resonances at low frequencies create negative bulk modulus and density. They use generalized effective medium formulas to show that under certain conditions, both the density and reciprocal of the bulk modulus decrease sufficiently to make the group velocity negative, leading to negative refraction. The study also shows that the double-negative band in the dispersion is not a result of band-folding due to Bragg scattering but is a consequence of resonances. The results are validated through transmittance calculations and are applicable even when shear wave components within the particles are considered.