The effects of dynamic laryngeal movements on pitch control

Extralaryngeal structures have been known to not only play an important role in swallowing, but also have a significant influence on the voice during phonation. The aim of this study is to evaluate the effect of dynamic laryngeal movements on pitch control.

Videofluoroscopic examinations were analyzed. To accurately analyze the sequence of these movements, the recorded images were digitized using a computer program. The moving distances of the hyoid bone, thyroid cartilage, and cricoid cartilage were analyzed, and they were compared to the cricothyroid distance during pitch elevation.

The vertical movements of the hyoid bone, and cricoid and thyroid cartilages had an impact on the increase in the pitch with a decrease in the cricothyroid distance. All Ad-R(2) values for distance of the hyoid bone, and cricoid and thyroid cartilages were above 0.9, which showed a higher explanatory power than the cricothyroid distance, showing an Ad-R(2) value of 0.4.

Upward movements of the larynx had a more dominant effect on pitch elevation than the cricothyroid distance. We suspect that the pitch is more affected by the antero-vertical movements of the larynx than the horizontal movement by cricothyroid muscle in human study.