Which sound is described as a harsh or high-pitched respiratory noise caused by an obstruction of the air passages?

Stridor refers to a harsh, high-pitched sound that is produced when there is an obstruction in the upper airways. This sound is typically heard during inhalation and can be a critical indicator of serious respiratory issues, such as laryngotracheobronchitis (croup) or anaphylaxis. The presence of stridor suggests that airflow is being disrupted at or near the level of the larynx, leading to turbulence and resulting in the characteristic wheezing noise.

In contrast, rales, which are also known as crackles, are fine, high-pitched sounds heard in the lungs, typically indicating fluid in the alveoli. Wheezes are continuous, musical sounds produced by narrowed airways, often associated with conditions like asthma or chronic obstructive pulmonary disease (COPD). Rhonchi are low-pitched, rattling sounds that occur when air passes through thick mucus in the airways, suggesting obstruction or inflammation in the bronchial passages. Each of these sounds has distinct characteristics and causes, but stridor specifically highlights an upper airway obstruction and is particularly critical in acute medical situations.