The vocal cords are located in the larynx and vibrate to produce sounds. They also prevent food from entering the airway during swallowing. There are two cords. If both become paralyzed and remain in the closed position, the airway can become obstructed. This requires emergent treatment. If only one is weakened patients have more problems with speech. Reasons for this disorder include: direct trauma to the cords, chest or neck surgery with an injury to the nerve supplying the cords, multiple sclerosis, stroke, and tumors.