In which direction do the vocal folds open during a cycle of vibration?

During a cycle of vibration, the vocal folds open from bottom to top and from posterior to anterior. This process begins with the lower edge of the vocal folds separating, creating a space that allows air from the lungs to pass through. As the air pressure builds up, the folds are pushed apart starting at the lower parts and moving upwards. The opening then progresses towards the front, resulting in the vocal folds being fully abduction at the anterior aspect last.

This movement is essential for the production of sound, as it allows the airflow to create pressure differences that contribute to the vibratory motion necessary for voice. Understanding this process is crucial for analyzing vocal production and addressing any speech-related disorders that involve issues with the vocal folds' function.