Let’s now consider how the vocal tract is used to make speech sounds. Firstly we need airflow; some mechanism to cause molecules of air to vibrate and so generate soundwaves. Most speech sounds are produced by getting the diaphragm muscles to contract and force air out of the lungs, passing out of the body through the nose or mouth.
Airflow generated by the lungs is called ‘pulmonic’ (meaning ‘of the lungs’). Airflow out of the lungs is called ‘egressive pulmonic’ airflow (egressive means ‘going out’).

Unsurprisingly, the vast majority of speech sounds in the world’s languages, in fact all sounds in most languages, are made with egressive pulmonic airflow. There are however some other minor types to be considered. Glottalic and Velaric airstreams both involve trapping pockets of air in the vocal tract, and manipulating the pressure of that air. We’ll also see that people who have had their larynges removed are able to generate airstream for speech in other ways. Click on the buttons below to explore these airstream mechanism types.