Illustration of oral air pressure (top), oral airflow (middle), and nasal airflow (bottom) during production of the syllable /pi/ repeated 7 times. Laryngeal airway resistance (LAR) during vowel production is estimated from interpolated oral pressure (dotted lines) and oral airflow. The interpolated pressures are considered to be equivalent to subglottal pressures during vowel production. An advantage of using the oral-nasal mask to determine LAR is that velopharyngeal closure can be confirmed from the nasal airflow trace.