Using the larynx to create an airstream

The larynx can bob up and down (you’ll have noticed this when you swallow). With a sealed oral cavity, bobbing the larynx down lowers air pressure and sucks air in. Sounds made this way are called ‘implosives’. Bobbing the larynx upwards increases air pressure and forces air out. Sounds made this way are called ‘ejectives’. We’ll just consider ejectives here and not worry about implosives.

Making ejective sounds

Close the vocal folds and velum, so you are “holding your breath’, and also make a stop closure for [k] in your vocal tract. You’ve now created a sealed-off pocket of air. Bobbing the larynx upwards into the pharynx reduces the volume of the air pocket, and thus increases its pressure. When you release the stop closure, air rushes out.
Play the animation to see this, and hear what it sounds like. Now try making an ejective [kʼ] for yourself. Can you feel that this sound does not involve pulmonary air, and you can make it while breathing both in and out?

Ejectives as speech sounds

Stops that are phonetically glottalic can sometimes be heard in English, usually word finally. Try saying ‘That’s sick!’ with a glottalic [kʼ] at the end. Note the small diacritic mark [ʼ] that indicates glottalic sounds.
Most glottalic sounds are stops (known as ‘ejectives’), and they are found in languages of the Caucasus, Africa and America. It is also possible to make glottalic affricates and fricatives in the same way.