What causes the audible sound of stridor?

• A. Excess moisture in the airways
• B. Turbulent airflow through an obstructed or narrowed segment of the airway
• C. Normal airflow through open airways
• D. Vocal cord vibration during speech

Answer: (B)

The sound of stridor is primarily caused by turbulent airflow through an obstructed or narrowed segment of the airway. When any part of the airway is constricted or obstructed, the airflow becomes turbulent as it passes through the narrowed space. This turbulence creates the characteristic high-pitched, wheezing sound that is associated with stridor. It indicates that there is an issue with the airflow in the upper respiratory tract, often due to conditions such as swelling, foreign body obstruction, or structural abnormalities.

In contrast, excess moisture in the airways does not create the turbulent flow necessary for the sound of stridor. Rather, it may facilitate smoother airflow. Similarly, normal airflow through open airways would not produce stridor, as there would be no obstruction to create turbulence. Finally, while sound from vocal cord vibration is part of normal phonation during speech, it does not relate to the pathological airflow dynamics that produce stridor. Therefore, the correct answer underscores the significance of airway obstruction in generating this specific sound.