A multiscale analytical model of bronchial airway acoustics

Area of Science:

• Biomedical Engineering
• Acoustics
• Pulmonary Medicine

Background:

• Understanding sound transmission in the respiratory system is crucial for diagnosing lung diseases.
• Previous models often assumed airway self-similarity, limiting their application to complex, subject-specific geometries.

Purpose of the Study:

• To develop and validate a computational model for calculating sound transmission and airway vibration in complex bronchial trees.
• To investigate the acoustic changes associated with pulmonary pathologies such as fibrosis, bronchoconstriction, and infiltrate.

Main Methods:

• A modified one-dimensional (1D) branching acoustic waveguide approach was used to model sound transmission.
• A detailed conducting airway model (approx. 60,000 branches) was adapted to simulate fibrotic, bronchoconstrictive, and pulmonary infiltrate conditions.
• Numerical and experimental validation was performed for the acoustic modeling approach.

Main Results:

• Fibrosis increased acoustic impedance and Helmholtz resonance frequency.
• Bronchoconstriction reduced acoustic energy transmission to peripheral airways due to impedance mismatch.
• Pulmonary infiltrate significantly altered the local acoustic field within the affected lung lobe.

Conclusions:

• Computational vibro-acoustic analysis can reveal pathology-specific changes in airway acoustics.
• These findings support the potential for acoustic methods to improve the diagnosis of pulmonary diseases.
• The developed model accommodates complex, non-self-similar airway geometries derived from medical imaging.