The rapid growth of renewable offshore energy development has raised concerns that underwater noise from construction and operation of offshore devices may interfere with communication of marine animals. An underwater sound model was developed to simulate sound propagation from marine and hydrokinetic energy (MHK) devices or offshore wind (OSW) energy platforms. Finite difference methods were developed to solve the 3-D Helmholtz equation for sound propagation in the coastal environment. A 3-D sparse matrix solver with complex coefficients was formed for solving the resulting acoustic pressure field. The complex shifted Laplacian preconditioner (CSLP) method was applied to solve the matrix system iteratively with Message Passing Interface (MPI) parallelization using a high-performance cluster. The sound model was then coupled with the Finite Volume Community Ocean Model (FVCOM) for simulating sound propagation generated by human activities, such as construction of OSW turbines or tidal stream turbine operations, in a range-dependent setting. As a proof of concept, the validation of the solver is tested with an ideal case against two other methods, and its application is then presented for two coastal wedge problems. This sound model can be useful for evaluating impacts on marine mammals due to deployment of MHK devices and OSW energy platforms.