V.N.Oliynik Features of wave propagation in the lung tissue |
Acoustic bulletin, Vol. 10 ¹ 2, (2007) |
| The paper deals with the problems of modeling wave properties of the lung tissue (parenchyma) and analyzing of extended experimental data on wave propagation in mammalian lungs within audible frequency range. Fundamentals of the theories are stated, that explain the formation of phase velocity and attenuation coefficient for bulk compression wave in such medium. For this purpose, the parenchyma may be considered as a suspension of gas bubbles with supported surfaces with simultaneous intensive heat exchange between gas and liquid phases induced by sound propagation. The analysis based on the Biot's theory for porous elastic media shows that the existence of the low-velocity wave, corresponding to quasistatic compression modulus for the lung, cannot be treated as a diffusive wave generated by gas motion with respect to the tissue "skeleton" of the lung. Apparently, phase velocity of the diffusive wave in this case corresponds to the waveguide type of sound propagation in the bronchial tree. It is assumed that the "low-frequency longitudinal" wave observed at local shock loading of the lung wall might be one of the structural nature. It is shown that the transversal wave recorded under these conditions may be easily identified using the known theories of mechanics of multiphase media. |
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KEY WORDS: lung tissue, a microstructured medium, macroscopic characteristics, compression wave, shear wave, diffusive wave |
| TEXT LANGUAGE: Ukrainian |