Auscultation is the technique of listening to the sounds of the chest with a stethoscope. The movement of air in and out of the respiratory system produces breath sounds. Breath sounds are transmitted through the chest wall and may be heard through the diaphragm (flat piece) of a stethoscope placed firmly against the chest wall. Auscultation of the lungs is the most important examining technique for assessing airflow through the tracheobronchial tree.

Ask the patient to sit with his arms folded across the chest with the hands resting, if possible, on the opposite shoulders. This position moves the scapulae partly out of the way and increases access to the lung fields. Instruct the patient to breathe deeply with his mouth open. Listen carefully for at least one full breath in each location. Observe the patient for light-headedness or fatigue and allow the patient to rest as often as necessary.

Start by listening to posterior chest, beginning with the areas above the scapulae. It is useful to start here because the lung fields are closer to the wall of the posterior chest and there's less interference from heart sounds than with the anterior chest. Move downward in a stair-step fashion, comparing your findings from one side with those from the other side. Chest auscultation involves: