Abstract

Nonlinear Vibroacoustic Processes on the Biological Tissue

I.Y.Demin (Nizhny Novgorod State University of Architectural and Civil Enginering, Nizhny Novgorod, Russia); B.N.Klochkov (Istitute of Applied Physics RAS, Nizhny Novgorod, Russia)

e-mail: physics@ngasu.sci-nnov.ru

The nonlinear properties of tissues in the process of their natural functioning are very important. The cases of single and two vibrators with different frequencies are considered. Low-frequency nonlinear acoustical properties of human forearm tissues are studied in relaxed state, in stressed state and in state of intensification blood filling. The highest nonlinearity level is observed in relaxed tissue state. When active muscle tension is developed the harmonics level falls essentially and tissue become more linear. The oedema tissue state takes an intermediate place near to the stressed state. Results of subharmonic measurements on tissue are presented. The vibroacoustic emissions from muscular layer reflect the state of tissue. For comparison it is investigated the tissue with volume, shear and surface waves. The considered acoustic phenomena on the surface and in the volume of a live tissue indicate an opportunity to study the tissue state by purely acoustic methods.

Section : 5