Boyle’s Law

Respiration is the power source for speech production in that it provides the necessary flow of air. The respiration mechanism can be explained [Page 296]in light of Boyle’s law. But before explaining respiration mechanics in this manner, it is necessary to first define some important pressures that develop in the thoracic cavity related to the inhalation and exhalation processes. Three different respiratory pressures are of particular relevance: intrapulmonary pressure, intrapleural pressure, and transpulmonary pressure.

Intrapulmonary pressure (Ppul) is the pressure within the lung’s alveoli; this pressure level is roughly 760 mm Hg, similar to atmospheric pressure because the alveoli are connected to the outside of the body through the bronchus and trachea. Intrapleural pressure (Pinp) is what exists in the pleural cavity, which is the space ...