Bone Conduction: A Linear Viscoelastic Mixed Lumped-Continuum Model for the Human Skin in the Acoustic Frequency Range

In conventional and skin-drive bone conduction, the performance of the exciter is strongly influenced by the mechanical impedance of the skin. This impedance is characterized by the resonance of the cutis on the underlying adipose layer. Although the existing Kelvin–Voigtbased lumped parameter skin model allows satisfactory approximation of the magnitude of the measured skin impedance, substantial deviations appear in the associated phase. The use of the existing skin model in coupled exciter-skin response calculations may thus lead to prediction errors at resonance peaks. The present work proposes an alternative model which considers the bending wave propagation in the cutis using a continuum model combined with a Zener material model for the underlying adipose tissue. It shows good agreement with the measurement results and leads to insights in the role of the different skin layers in the observed dynamic response.