Final answer:
Stridor is the abnormal breath sound that indicates obstruction of the upper airway, typically in the throat or larynx.
Step-by-step explanation:
The abnormal breath sound that indicates obstruction of the upper airway is stridor. Stridor is a high-pitched, wheezing sound that is heard during inhalation and indicates a narrowing or blockage of the upper airway, typically in the throat or larynx. It can be caused by conditions such as croup, epiglottitis, or vocal cord dysfunction.