The shouted voice: A pilot study of laryngeal physiology under extreme aerodynamic pressure.

Introduction: The objective was to study the behavior of the larynx during shouted voice production, when the larynx is exposed to extremely high subglottic pressure.
Materials and Methods: The study involved electroglottographic, acoustic, and aerodynamic analyses of shouts produced at maximum effort by three male participants.
Results and Discussion: Under a normal speaking voice, the voice sound pressure level (SPL) is proportional to the subglottic pressure. However, when the subglottic pressure reached high levels, the voice SPL reached a maximum value and then decreased as subglottic pressure increased further. Furthermore, the electroglottographic signal sometimes lost its periodicity during the shout, suggesting irregular vocal fold vibration.