mechanism
Last reviewed 01/2018
Traditionally, it has been suggested that wheezes are produced in a manner similar to an organ pipe: the physical properties of the tube - bronchus - set the column of air within into a state of oscillation as it passes through. However, the length of the maximum vibratory path does not co-incide with the low frequencies which can be produced, and, the note produced is altered by changes in gas density, unlike physiological wheezes.
Instead, a simple reed instrument seems to be a better paradigm. It is the walls of the bronchi which vibrate at a given frequency between occluded and partially open states. This explains both the variation of the quality of wheezes with the respiratory cycle and why high pitched wheezes can be auscultated at either central or peripheral stations over the chest.