Which airway sound indicates a lower airway obstruction?

Wheezing is the sound that indicates a lower airway obstruction. This high-pitched, musical sound occurs when airflow is partially blocked in the lower airways, specifically in the bronchi and bronchioles. It is commonly associated with conditions like asthma or chronic obstructive pulmonary disease (COPD), where inflammation and bronchoconstriction lead to narrowed airways.

In contrast, stridor is typically associated with upper airway obstructions and presents as a harsher, more pronounced noise during inhalation. Crowing, which often resembles a sound made during inspiration, is also indicative of upper airway issues. Gurgling usually occurs with fluid or secretions in the upper airways and doesn't reflect the lower airway conditions. Thus, wheezing specifically points to issues within the lower airway, making it the correct choice.