What does the relationship between supraglottic and subglottic pressure determine?

The relationship between supraglottic and subglottic pressure is crucial in determining the vibratory function of the vocal folds. Subglottic pressure is the air pressure that builds up beneath the vocal folds, while supraglottic pressure refers to the pressure found above the vocal folds, in the throat and oral cavity.

When subglottic pressure increases, it provides the necessary force for the vocal folds to be impacted, allowing them to vibrate effectively. This pressure difference is what initiates sound production during phonation. Proper balance and manipulation of these pressures enable the vocal folds to open and close at an adequate rate, impacting how they vibrate and, subsequently, how sound is produced.

While pitch is influenced by factors such as tension and mass of the vocal folds, and sound volume is affected by airflow and pressure levels, the specific relationship of supraglottic and subglottic pressures is directly related to the engagement and function of the vocal folds themselves in creating sound.