An experimental approach for estimating the impedance of elastic non-porous materials

Human skin is generally assumed to be acoustically rigid. It has been shown that it almost totally reflects sound
waves, without significant dissipation of energy. Yet, it appears that the propagation of sound around the human
body is influenced by the acoustic properties of skin tissue (this is for example observed in the simulation of
head-related transfer functions or in ear-canal reflectance measurements). In general, estimating the impedance
of highly reflective materials is experimentally challenging. In this work, the feasibility of the impedance
estimation of nearly acoustically rigid bodies via the equivalent source method is assessed. A semi-analytical
solution to the problem of scattering of sound by an elastic body with a rigid core is derived. The solution of
this problem is used as a validation benchmark for the proposed impedance estimation method. Experimental
tests with real data are also presented and compared against the model result.