Maximum phonation time (MPT) is defined as:

• A. The maximum rate of airflow through the vocal folds.
• B. The minimum lung pressure for phonation.
• C. The duration of the longest sustained vowel at a given normal airflow.
• D. The maximum time that a vowel may be sustained using maximum airflow.

Answer: (D)

Maximum phonation time is a measure of how long a person can sustain a vowel on one breath with a steady, comfortable voice. It reflects how efficiently the vocal mechanism uses breath and maintains continuous vibration of the vocal folds. In practice, the person takes a single deep breath and sustains a vowel (usually /a/) at a normal pitch and loudness, and the duration is recorded. This is not about the maximum rate of airflow, nor the minimum lung pressure, and it isn’t about sustaining with maximum airflow. The key idea is the longest possible phonation on a single breath under comfortable speech conditions.