V.G.Basovsky, I.V.Vovk, O.I.Vovk Sound propagation in human bronhial tree. Part II. Analysis of numerical results |
Acoustic bulletin, Vol. 3 ¹ 4, (2000) |
| On basis of developed in the previous paper the solution algorithm of problem concerned with propagation of the sound waves in a bronchial tree the acoustic properties of human bronchial tree are numerically investigated. In particular, the imaginary part of an entry impedance of a bronchial tree is demonstrated to have resonanses and antiresonanses following one after another. Considerable "peaks" of the real part of an impedance therewith are found on the antiresonance frequencies, while "dips" on the resonances. A comparison between designed and experimental values of an input impedance is conducted and their satisfactory coincidence is installed. A distribution of the sound energy flows in a bronchial tree is studied. It is shown that the energy in the sound propagation process damps rather quickly at the expense of losses in viscoelastic walls of pneumatic paths and reradiation by walls of the energy in the surrounding biotissue. The essential dependence is installed for phase velocity of the sound inside a bronchial tree as from frequency, as from choice of the initial and the final points of a bronchial tree site, for which this velocity is estimated. It is demonstrated that this speed can be much below and above the sound speed in the free air environment. Possible delay factor of the sound signal at its passing from the onset of trachea's up to the thorax surface is estimated. |
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KEY WORDS: bronchial tree, acoustic energy, re-radiation, delay time |
| TEXT LANGUAGE: Russian |