File:Fig.1. The Vocal Cords..JPG

English: Positioned at the base of the larynx in the vocal tract, these twin layers of mucous membrane act as the vibrator during phonation. Open during breathing, the folds are closed by the pivoting of the arytenoid cartilages for speech or singing. Positive air pressure from the lungs forces them open momentarily, but the high velocity air produces a lowered pressure by the “Bernoulli” effects which bring them back together. The folds themselves have a resonant frequency which determines voice pitch