Airstream and phonation

This airflow can be produced at different places and it can go in to directions - outwards, i.e. egressive, or inwards, i.e. ingressive. In English, as in many other languages, the sounds are produced with air moving out of the lungs. But how do we actually manage to produce sounds? It all starts in our larynx or the voice box:

Vocal Sound Production Diaphragm action pushes air from the lungs through the vocal folds, producing a periodic train of air pulses. This pulse train is shaped by the resonances of the vocal tract. The basic resonances, called vocal formants, can be changed by the action of the articulators to produce distinguishable voice sounds, like the vowel sounds.	Index Voice concepts Musical instruments
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(Image source: http://hyperphysics.phy-astr.gsu.edu/hbase/music/voice.html)

1. vocal folds are being drawn together fairly tightly;
2. air pressure builds up from below and forces the vocal folds apart;
3. sudden release of the vocal folds reduces the pressure and the vocal folds are pulled back together (Bernoulli effect);
4. pressure builds up again and the cycle repeats itself (many times per second).

During respiration the vocal folds are separated (abducted), allowing air to move freely in and out of the body. The fact that the vocal folds can intrude on the airstream (adduct) and form a constriction of the airway is a critical part of phonation. The airstream is forced to make a detour around the vocal folds, and it is under these conditions that the Bernoulli Effect occurs.