vocal cords

The vocal cords are two small bands of tissue stretched across the inside of the voice box, like the reeds of a wind instrument. When you breathe quietly they part to let air pass; when you speak or sing they come together and flutter in the airstream to make sound.

More precisely called the vocal folds, they sit at the narrowest point of the upper airway, the space between them being the glottis. Muscles and cartilages in the larynx adjust their tension and position, which is how pitch and loudness change. They also slam shut to protect the lungs during swallowing and build the pressure needed for an effective cough.

When the cords are inflamed (laryngitis), paralysed, or moving abnormally, the voice becomes hoarse or breathing becomes noisy. Paradoxical vocal-cord movement can even mimic asthma, which is why persistent hoarseness or stridor deserves a proper look at the larynx.