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How do the lungs provide the airflow needed for human speech?

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Uncover the science behind the transformation of sounds into speech — speech Speech is the faculty of producing articulated sounds, which, when blended together, form language.

The lungs provide the necessary airflow for human speech through a specialized process known as phonic respiration, which differs significantly from quiet breathing.1

To produce speech, an individual takes a deep, rapid inhalation, drawing in one to two liters of air. During the subsequent exhalation, the diaphragm—the primary muscle of respiration—and other respiratory muscles work to provide a steady, controlled stream of air. This air is driven upward through the trachea toward the larynx.1234

As this pressurized air reaches the vocal cords, it encounters resistance. According to the myoelastic theory of voice production, the subglottic pressure builds until it overcomes the tension of the vocal cords, causing them to vibrate as air puffs escape. This mechanical process transforms the energy of the moving airstream into audible sound, which is then shaped into speech by the pharynx, tongue, and lips. The nervous system constantly regulates these movements to adjust for the intensity and emotional quality of the utterance.341