Final answer:
Stridor is the high-pitched sound indicating swelling of the upper airway, it is usually heard during inhalation, and typically suggests an underlying condition causing airway narrowing.
Step-by-step explanation:
The sound that indicates swelling of the upper airway is stridor. This is a high-pitched, wheezing sound that is particularly noticeable when a person inhales. It can be caused by several conditions such as allergic reactions, infections, and obstructions that result in the narrowing of the airway. Stridor is different from other respiratory sounds, such as wheezing, which generally indicates an obstruction in the lower respiratory tract and is a common symptom in conditions like asthma. Another sound, rales, are crackling, rattling breath sounds suggesting fluid in the air spaces of the lungs, which are commonly heard in pneumonia. Rhonchi are low-pitched sounds resembling snoring or gurgling, often associated with conditions causing obstruction of the larger airways, such as chronic bronchitis.