How is subglottal pressure maintained during speech?

• A. By using only passive forces
• B. Through balanced active and passive forces
• C. By increasing lung volume
• D. Only through muscular contractions

Answer: (B)

Subglottal pressure is critical for phonation and is maintained through a combination of active and passive forces acting on the respiratory system.

Active forces come from muscular contractions, particularly from the muscles controlling the diaphragm and intercostal muscles that help regulate lung volume and, consequently, the air pressure beneath the vocal folds. These contractions actively increase the volume of air available for speech production, thereby influencing subglottal pressure.

On the other hand, passive forces play a role as well. These are the natural elastic properties of the lungs and thoracic cavity, which help in maintaining a stable air pressure balance. The stretch of lung tissue due to the air within creates a passive force that supports subglottal pressure when the muscles are not actively engaged.

This interplay between active and passive forces allows for a flexible and efficient control of subglottal pressure, adjusting as needed to produce different speech sounds. This aspect is why balanced active and passive forces are crucial for maintaining adequate subglottal pressure during speech.