Normal breath sounds are classified as tracheal, bronchial, bronchovesicular, and vesicular sounds. The patterns of normal breath sounds are created by the effect of body structures on air moving through airways. In addition to their location, breath sounds are described by:
Tracheal breath sounds are heard over the trachea. These sounds are harsh and sound like air is being blown through a pipe.
Bronchial sounds are present over the large airways in the anterior chest near the second and third intercostal spaces; these sounds are more tubular and hollow-sounding than vesicular sounds, but not as harsh as tracheal breath sounds. Bronchial sounds are loud and high in pitch with a short pause between inspiration and expiration; expiratory sounds last longer than inspiratory sounds.
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Bronchovesicular sounds are heard in the posterior chest between the scapulae and in the center part of the anterior chest. Bronchovesicular sounds are softer than bronchial sounds, but have a tubular quality. Bronchovesicular sounds are about equal during inspiration and expiration; differences in pitch and intensity are often more easily detected during expiration.
Vesicular sounds are soft, blowing, or rustling sounds normally heard throughout most of the lung fields. Vesicular sounds are normally heard throughout inspiration, continue without pause through expiration, and then fade away about one third of the way through expiration.
In a normal air-filled lung, vesicular sounds are heard over most of the lung fields, bronchovesicular sounds are heard between the 1st and 2nd interspaces on the anterior chest, bronchial sounds are heard over the body of the sternum, and tracheal sounds are heard over the trachea.
Normal findings on auscultation include: