High efficient and quiet propulsion of flying and swimming animals promotes the investigations on acoustic scattering and flow-induced noise. One challenge for aero/hydro-acoustic simulation is the treatment on complex and moving solid boundaries, with retaining high-order accuracy. In this paper, a sharp interface immersed boundary method (IBM) was implemented in both fluid dynamics and aero/hydro-acoustics, within a hybrid approach. The hybrid approach combined a high-fidelity DNS solver for flow field and a low-dispersion, low-dissipation acoustic solver, with optimized computational aeroacoustic schemes, using the acoustic perturbation equations (APEs). A series of benchmark problems on aeroacoustic propagation and scattering acoustic fields with a cylinder or sphere scatterer were computed to validate the accuracy and boundary condition treatments of the acoustic solver, in two dimension and three dimension. Following this, the flow field and flow-induced noise of flow past a stationary cylinder, with Reynolds number 200 was presented. With the hybrid approach proposed in the paper, the potential for dealing with bio-inspired problems in flying and swimming animals is indicated.