Normal subglottal pressure values for adults are in which range?

• A. 4-10 cm H2O
• B. 1-3 cm H2O
• C. 10-15 cm H2O
• D. 0-2 cm H2O

Answer: (A)

Subglottal pressure is the driving pressure beneath the vocal folds that enables phonation. For normal adult conversational speech, this pressure sits a few centimeters of water, reflecting the balance between lung effort and vocal fold resistance. The range 4–10 cm H2O captures typical variation across individuals and speaking styles—from softer, everyday speech to louder or more forceful voicing. Values near the lower end are enough for ordinary voice, while pressures up toward 10 cm H2O are common when speaking more loudly or with greater vocal effort. Pressures well below this range would make phonation difficult, and much higher pressures would indicate very loud or stressed phonation beyond normal everyday speech. That’s why the 4–10 cm H2O range is the best fit for normal adult subglottal pressure.