  Hybrid aeroacoustic methods seek for computational efficiency and robust
noise prediction. Using already existing aeroacoustic wave equations, we
propose a general hybrid aeroacoustic method, based on compressible source
data. The main differences to current state of the art aeroacoustic analogies
are that an additional decomposition is used to compute the aeroacoustic source
terms and their application is extended to the source formulation, based on
compressible flow data. By applying the Helmholtz-Hodge decomposition on
arbitrary domains, we extract the incompressible projection (non-radiating base
flow) of a compressible flow simulation. This method maintains the favorable
properties of the hybrid aeroacoustic method while incorporating compressible
effects on the base flow. The capabilities are illustrated for the aeroacoustic
benchmark case, "cavity with a lip", involving acoustic feedback. The
investigation is based on the equation of vortex sound, to incorporate
convective effects during wave propagation.
