That harsh, high-pitched breathing sound you’re hearing is called stridor. Stridor = upper airway narrowing, usually around the larynx or trachea — and it sounds loudest when a child breathes in. In this little girl, the cause is FLU A. Flu can cause significant inflammation in the upper airway, especially in young children, leading to swelling that creates this scary sound. What parents should know: • Stridor is different from wheezing (which comes from the lungs) • It often sounds harsh, tight