Occasionally, a person may choke when food gets past the epiglottis or sticks to a structure within the pharynx and blocks the airway. The vocal folds contract to catch the blockage before it passes into the trachea. Coughing pushes air out of the lungs to force the blockage out of the airway. Sounds are produced in the larynx by the movement of air through the larynx and by the vocal folds, a pair of movable folds in the mucous membrane.