Breath sounds originate in the large airways where air velocity and turbulence induce vibrations in the airway walls. These vibrations are then transmitted through the lung tissue and thoracic wall to the surface where they may be heard readily with the aid of a stethoscope. Breath sounds can be classified into two categories, either normal or abnormal. You can hear examples of breath sounds by clicking on the links.
Abnormal Sounds: Bronchovesicular - consist of a full inspiratory phase with a shortened and softer expiratory phase.
Crackle - sounds heard at the end of a deep breath. Stridor - high pitched sound resulting from turbulent gas flow in the upper airway. Tracheal - strong and covers a wider frequency range than lung sound. Wheeze - continuous, coarse, whistling sound produced in the respiratory airways during breathing.