Respiratory disorders are common in both developed and developing countries. Many of these disorders are directly connected to constrictions in the airways of the human respiratory system. Asthma and bronchitis are typical examples that arise from the constriction of airways. The respiratory system consists of a series of branching tubes which become narrower, shorter and more numerous as they penetrate deeper into the lung. This branching network found within the multiple succussive bifurcation of the pulmonary tree has received theoretical attention . Several attempts have been made to investigate the characteristics of healthy and unhealthy lungs. Some of them theoretical [2–5] while others are experimental [6,7]. The acoustical approach has been considered as one of the leading theoretical approaches to date. This approach is based on linking the acoustical impedance between the branches by using recursive formulae . None of the available references has investigated the effect of occlusions in a branch on the behaviour of the whole respiratory system. Further, the work reported on the dynamic modelling of the respiratory system has overlooked, with the exception of , mechanical and physical properties of the airway walls, which are believed to have a considerable impact on the overall dynamics of the system.