The Vocal folds are also known as the vocal cords. The Vocal folds are twin folding mucus membranes that are stretched horizontally, from back to front, across the larynx. When they vibrate, they regulate the flow of air that is being expelled from the lungs during singing.
"Vocal Folds." ScienceDaily. ScienceDaily, n.d. Web. 26 Mar. 2015.