A two-dimensional acoustic topological insulator with an acoustic analog of the quantum spin Hall effect is experimentally and theoretically demonstrated. The system consists of two graphene-like acoustic crystals with different rod radii, forming a waveguide that supports robust one-way sound propagation. This phenomenon arises from band inversion near double Dirac cones, leading to spin-dependent edge states that are immune to defects and disorders. The topological protection ensures that sound propagates without backscattering, making it useful for acoustic devices like isolators, filters, and splitters. The concept of topology, originally from mathematics, is used to classify materials based on their quantum behaviors. In condensed matter physics, topological insulators exhibit robust one-way transport due to protected edge states. For acoustic systems, this is achieved by designing structures that mimic the quantum spin Hall effect, using acoustic spin and spin-orbit coupling. The key is to create four-fold degenerate states at the Brillouin zone center, which split into two-fold states and open a bulk gap, enabling topological transitions. The study shows that acoustic topological states can be realized using simple structures without external forces, offering a promising platform for acoustic wave manipulation. The robustness of these states against defects is verified through experiments, demonstrating that sound can propagate without significant loss even in the presence of cavities, disorder, and bends. The results highlight the potential of acoustic topological insulators in applications such as sound guiding, communication, and spin-based acoustic devices. The findings also suggest that similar phenomena can be extended to other classical wave systems, providing new insights into wave propagation and topological physics.A two-dimensional acoustic topological insulator with an acoustic analog of the quantum spin Hall effect is experimentally and theoretically demonstrated. The system consists of two graphene-like acoustic crystals with different rod radii, forming a waveguide that supports robust one-way sound propagation. This phenomenon arises from band inversion near double Dirac cones, leading to spin-dependent edge states that are immune to defects and disorders. The topological protection ensures that sound propagates without backscattering, making it useful for acoustic devices like isolators, filters, and splitters. The concept of topology, originally from mathematics, is used to classify materials based on their quantum behaviors. In condensed matter physics, topological insulators exhibit robust one-way transport due to protected edge states. For acoustic systems, this is achieved by designing structures that mimic the quantum spin Hall effect, using acoustic spin and spin-orbit coupling. The key is to create four-fold degenerate states at the Brillouin zone center, which split into two-fold states and open a bulk gap, enabling topological transitions. The study shows that acoustic topological states can be realized using simple structures without external forces, offering a promising platform for acoustic wave manipulation. The robustness of these states against defects is verified through experiments, demonstrating that sound can propagate without significant loss even in the presence of cavities, disorder, and bends. The results highlight the potential of acoustic topological insulators in applications such as sound guiding, communication, and spin-based acoustic devices. The findings also suggest that similar phenomena can be extended to other classical wave systems, providing new insights into wave propagation and topological physics.