The effects of dynamic laryngeal movements on pitch control.

ABSTRACT

BACKGROUND AND OBJECTIVES: 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. SUBJECTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.