The term vocal cords can be somewhat misleading because these sound producing structures are not really chords but are folds of expandable tissue that extend across a hollow chamber known as the voice box. When engaged for speaking, the vocal folds can clock over 100 vibrations per second -- too fast for the unassisted eye to see. The voice box or larynx is located directly above the windpipe, which leads to the air passages of the lungs. When not used in speech, vocal cords remain open and lie close to the mucous membrane lining of the larynx. This provides flowing air with a direct and unobstructed pathway to the lungs and is vital for undisturbed breathing. Pitch is determined by frequency of the vibrations and higher-pitched sounds are typically produced by shorter and thinner folds that more often manifest in women and young children.