Function

The main function of the larynx is protect the inlet of airway – viz. as in birds, they close the larngeal inlet (rima glottis, the true vocal cords), but can still produce sound by passing air through the syrinx, a dilatation just above the bifurcation of the trachea. So phonation in human is extra.

Lungfish

Lungfish can breath both in air through lungs and water through gills as follows:

Water breathing: Spiral valve of conus arteriosus open; 3+4 arches closed; 2, 5+6 open; ductus arteriosus open; pulmonary arteries closed.

Lung breathing: Spiral valve closed; 3+4 arches open;  2,5 +6 closed; ductus arteriosus closed; pulmonary arteries opened.

Neonatal

Intranarial larynx that descends later on, by first year of life.