This contribution reports about the progress on a
FEM-based approach to solve the inverse acoustic
problem of an internal space considering admittance
boundary condition, called IFEM. In spaces bounded
by structures with complex geometry it is difficult to
measure directly the boundary admittance, that is
an essential parameter for acoustic simulations.
The authors have not found any methods in literature
to globally estimate the boundary admittance
of arbitrarily shaped cavities by using inverse
methods. Apparently, in inverse acoustics two major
types of algorithms are developed usually to detect
sources. There is the near-field acoustic holography
(NAH) [1,2] and the inverse frequency response function
(IFRF), also called inverse boundary element
method (IBEM) [3-8]. A so-called hybrid NAH [9]
was developed to combine the advantages of NAH
and IBEM. Although this method is applicable to
arbitrarily shaped surfaces, it does still not consider
or calculate admittance boundary conditions.