The air pressure in the lungs during speech or singing supplies the energy that generates the human voice. This lung pressure is also commonly referred to as the subglottal pressureSubglottal pressure, or Subglottic pressure, is the pressure that builds up beneath (“Sub-”) the vocal folds. The amount of subglottal pressure generated is determined by the airflow through the leakage of air between the vocal folds and the resistance to that flow or tracheal pressure, though these are all technically slightly different. We will hereafter use the term subglottal pressureSubglottal pressure, or Subglottic pressure, is the pressure that builds up beneath (“Sub-”) the vocal folds. The amount of subglottal pressure generated is determined by the airflow through the leakage of air between the vocal folds and the resistance to that flow.

Knowledge of the subglottal pressureSubglottal pressure, or Subglottic pressure, is the pressure that builds up beneath (“Sub-”) the vocal folds. The amount of subglottal pressure generated is determined by the airflow through the leakage of air between the vocal folds and the resistance to that flow driving the laryngeal voice source is very important in understanding the operation of the voice. Until recently, the subglottal pressureSubglottal pressure, or Subglottic pressure, is the pressure that builds up beneath (“Sub-”) the vocal folds. The amount of subglottal pressure generated is determined by the airflow through the leakage of air between the vocal folds and the resistance to that flow has been difficult to measure non-invasivelyA non-invasive measurement is one that does not require the introduction of instruments into the body.. The PG-20 and PG-60 use a version of the intraoral pressurePressure within the mouth when the lips and the velopharyngeal passageway are closed interpolation technique introduced by Glottal Enterprises founder Martin Rothenberg (J. Acoustic Society of America 53, 1632–1645). Real-time operation is accomplished by means of a unique patented electronic circuit. In the PG-20/PG-60, the intraoral pressurePressure within the mouth when the lips and the velopharyngeal passageway are closed during a /p/ consonant is recorded by means of a pressure transducer within the unit that is accessed via a standard Luer connector on the end of the unit. The PG-20 is supplied with a number of pressure sensing tubes, each with a mating Luer connector. The probe tube for the oral pressure transducer should be placed between the subject's lips, usually in the corner of the mouth, where it is least affected by lip motion.