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How do the vocal cords in the larynx produce sound?

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Illustration showing different animals and their respiratory organs: a spider with book lungs, a chicken with lungs, a sponge with labeled inflow and outflow pores, a fish with gills, and a caterpillar with spiracles. — Respiratory system Different methods of respiration in animals.

The vocal cords, located within the larynx, produce sound through a process described by the myoelastic-aerodynamic theory.1

During phonation, the vocal cords are brought together (adducted) by muscles, closing the glottis. Air exhaled from the lungs is driven upward through the trachea, creating subglottic pressure against the underside of the cords. When this pressure becomes sufficient to overcome the closing force of the cords, the glottis is forced open, allowing a puff of air to escape.21

Following this release, the reduction in subglottic pressure, combined with the elasticity of the vocal cords and the aerodynamic effects of the moving air, causes the cords to snap shut again. This cycle of opening and closing repeats rapidly, creating vibrations that generate sound. The frequency of these vibrations determines the pitch of the voice, while the tension of the cords and the force of the airstream regulate the sound's characteristics. Once produced, this raw sound passes into the upper cavities to be shaped and articulated into speech.132