Sudden airway obstruction, or choking, may be either mild (partial) or severe (complete).
If the obstruction is mild, breathing may be noisy and the casualty may be able to cough or speak. In such cases, encourage coughing and seek medical assistance.
If the obstruction is severe the casualty will soon become unconscious. Be aware that severe airway obstruction is silent as there is no movement of air to allow for speaking or breathing.