The concept of topological insulators has attracted significant interests due to the presence of topologically protected states following the bulk-boundary correspondence. Higher-order topology has extended this principle and hosts lower-dimensional topological corner states. Recent studies have shown that the hybridization of a gapless bulk state and nontrivial topology could lead to a large-area topological state in classical systems. In this Letter, we design an acoustic heterostructure that hybridizes a second-order topological insulator layer with a Dirac material layer, based on the Benalcazar-Bernevig-Hughes model. This hybrid system generates a topological hybrid corner state pinned at zero energy within a complete band gap. Crucially, this topological hybrid corner state exhibits tunable large-area localization controlled by the number of outer layers and the coupling strength of the inner region. Furthermore, we experimentally demonstrate this state through pressure field distributions and intensity spectra, showing excellent agreement with simulations and theoretical analyses. The stable eigenfrequency and scalable confinement area of the large-area corner state provide the possibility to advance functional acoustic devices, such as energy harvesters or broadband sensors, where adaptable wave control is essential.

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• Acoustic metamaterials
• Topological effects in acoustic systems
• Topological metamaterials
• Tight-binding model