Kinematics of the Chest Wall during Speech Production: Volume Displacements of the Rib Cage, Abdomen, and Lung

Abstract

The chest wall has been treated as a two-part kinematic system comprised of the rib cage and diaphragm-abdomen in parallel, and wherein the volume displaced by each part is linearly related to the motions of points within it. Using measurements of changes in anteroposterior diameters of the rib cage and abdomen, we studied subjects in upright and supine postures during several respiratory maneuvers and utterance tasks. Results are charted in relative motion diagrams (rib cage vs abdomen), which include the relaxed configuration of the chest wall and departures therefrom during utterances. For conversation, reading, and singing, lung volume events were restricted to the midvolume range and were dependent upon body posture and utterance loudness. Relative volume contributions of the two parts differed for subjects and utterances and ranged from all rib cage displacement to all abdominal displacement. During utterances, the chest wall was distorted from its relaxed configuration, and differently so in the two postures studied. Potential mechanisms responsible for these distortions are discussed. We conclude that the distortions observed constitute a “volume platform” or posturing of the chest wall, off of which the speaker produces speech but does not significantly further distort the system in providing the changes in driving pressure required for typical utterances.