This paper addresses the challenges in studying the interaction between highâintensity sound waves and largeâdeformable hyperelastic solids, which are characterized by nonlinearities of the hyperelastic material, the finiteâamplitude acoustic wave, and the largeâdeformable fluidâsolid interface. An implicit coupling method is proposed for predicting nonlinear structuralâacoustic responses of the largeâdeformable hyperelastic solid submerged in a compressible viscous fluid of infinite extent. An arbitrary LagrangianâEulerian (ALE) formulation based on an unsplit complexâfrequencyâshifted perfectly matched layer method is developed for longâtime simulation of the nonlinear acoustic wave propagation without exhibiting longâtime instabilities. The solid and acoustic fluid domains are discretized using the finite element method, and two different options of staggered implicit coupling procedures for nonlinear structuralâacoustic interactions are developed. Theoretical formulations for stability analysis of the implicit methods are provided. The accuracy, robustness, and convergence properties of the proposed methods are evaluated by a benchmark problem, that is, a hyperelastic rod interacting with finiteâamplitude acoustic waves. The numerical results substantiate that the present methods are able to provide longâtime steadyâstate solutions for a nonlinear coupled hyperelastic solid and viscous acoustic fluid system without numerical constraints of small time step sizes and longâtime instabilities. The methods are applied to investigate nonlinear dynamic behaviors of coupled hyperelastic elliptical ring and acoustic fluid systems. Physical insights into 2:1 and 4:2:1 internal resonances of the hyperelastic elliptical ring and periodâdoubling bifurcations of the structural and acoustic responses of the system are provided.