A hybrid computational two-step approach is proposed for predicting turbulence-related noise. Initially, the unsteady compressible flow field is computed within the acoustic source region using large eddy simulation (LES). Given the significant scale disparity between acoustic and hydrodynamic fields in low Mach number flows, the acoustic field is subsequently calculated using linear acoustic equations, incorporating sources derived from the unsteady flow field. The acoustic computation domain extends into the near far-field and includes parts of the surface geometry not resolved by the local LES. A set of acoustic perturbation equations (APE) is developed to simulate flow-induced acoustic fields while preventing unbounded growth of hydrodynamic instabilities in critical mean flows. The first part of the work focuses on implementing and validating numerical methods for discretizing the linearized Euler equations as governing acoustic equations within computational aeroacoustics (CAA). The second part applies these equations to airframe noise issues, using laminar flow over a cylinder at Mach number M=0.3 and Reynolds number Re=200 as a test case for comparing sound source formulations. Additionally, the hybrid approach is utilized to predict trailing edge noise for a flat plate at M=0.15 and Re = 7 × 10^5, with the vortex source term based on Lamb's vector, applicable to both incompressible and compressible LES. This source al
