V.N.Oliynik On mechanisms of formation of the pulmonary parenchyma acoustic properties |
Acoustic bulletin, Vol. 4 ¹ 3, (2001) |
| The anatomic structure of a human respiratory system is analyzed. For the frequencies characteristic to the breath sounds the possibility of representing the lung's respiratory zone as a continuum with microstructure is justified. An acoustic model of the lung parenchyma is developed on the basis of physical study of the dispersion and the sound attenuation in emulsions. For the case of thermal independence of grains of emulsion (alveoles) the analytical expression describing the sound speed and the attenuation coefficient in parenchyma is obtained. It is shown, that the behavior of the sound speed foreseen in the emulsion model is similar to the tendencies depicted by the simple gas-liquid models. A strong dependence of the attenuation coefficient on the frequency and concentration of the parenchyma's gas phase is established. It is outlined, that at low values of lung's filling by air the frequency dependence of damping in the studied range is the quadratic one. As for high values, it demonstrates the transfer to the root tendency with a growth of a frequency. This peculiarity is conditioned by a strong resizing of alveoles during the respiratory cycle. Considerable decrease of the sound attenuation at deep inspiration is stated. |
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KEY WORDS: parenchyma, alveole, gas-liquid emulsion, the interphase, heat transfer, thermal dispersion, heat dissipation |
| TEXT LANGUAGE: Russian |