The primary function of larynx is:

Explanation

The larynx houses the vocal cords, and air forced between them makes them vibrate to produce sound, which is why it is called the voice box. Humidifying and filtering the air are done earlier, in the nasal cavity and the ciliated mucous lining of the airways. Gaseous exchange happens only in the alveoli, since no other part of the tract has walls thin enough.